WorldWideScience

Sample records for biological fouling

  1. CFD Simulation of Fouling by Biological materials in Membrane Bioreactor

    Directory of Open Access Journals (Sweden)

    Raziye, Ahmadi

    2016-06-01

    Full Text Available In recent years membrane bioreactors filtration is increasingly used in wastewater treatment to enhance the quality of wastewater. The main problem in preventing the widespread use of membrane bioreactor is its congestion which has a severe impact on output flux to time ratio. If solid suspensions with high concentrations exist in the wastewater, this influence will be even more severe. In addition to the suspended solids in the liquid mixture, Extracellular polymeric materials (EPS and soluble microbial products (SMP are also known as basic microbial products that cause membrane fouling. EPS can be calculated within and on the membrane which increases the viscosity of suspended solids in the liquid mixture and increases filtration resistance. SMPs cannot penetrate the pores of the ultra filtration membrane due to the limited size of the pores which would cause fouling in membrane processes. According to the above issues, providing a model that indicates the properties and conditions of formation and destruction of SMP and EPS at the same time seems necessary. In this paper, CFD simulation of biological fouling in membrane bioreactor is provided using Fluent software.

  2. Contribution of assimilable organic carbon to biological fouling in seawater reverse osmosis membrane treatment.

    Science.gov (United States)

    Weinrich, Lauren; LeChevallier, Mark; Haas, Charles N

    2016-09-15

    Biological fouling occurs on RO membranes when bacteria and nutrients are present in conditions that are conducive to growth and proliferation of the bacteria. Controlling microbial growth on the membranes is typically limited to biocide application (i.e., disinfectants) in seawater RO plants. However, biological growth and subsequent fouling has not been well-managed. Pretreatment has not been focused on nutrient limitation. This project used a biological assay, the assimilable organic carbon (AOC) test to evaluate pretreatment effects on the nutrient supply. The AOC test provided a useful surrogate measurement for the biodegradability or biofouling potential of RO feed water. Biofouling observed in controlled conditions at the bench- and pilot-scale resulted in statistically significant correlations between AOC and the operational effects caused by biofouling. Membrane fouling rates are observed through operational changes over time such as increased differential pressure between the membrane feed and concentrate locations and decreased permeate flux through the membrane. In full scale plants there were strong correlations when AOC was used as a predictor variable for increased differential pressure (0.28-0.55 bar from September-December 2012) and decreased specific flux (1.40 L per hour/(m(2) · bar)). Increased differential pressure was associated with RO membrane biological fouling when the median AOC was 50 μg/L during pilot testing. Conditions were also evaluated at the bench-scale using a flat sheet RO membrane. In a comparison test using 30 and 1000 μg/L AOC, fouling was detected on more portions of the membrane when AOC was higher. Biofilm and bacterial deposits were apparent from scanning electron microscope imaging and biomass measurements using ATP.

  3. Biological control of fouling incrustation on the scallop Nodipecten nodosus (Linnaeus, 1758 cultured in Ubatuba, SP, Brazil

    Directory of Open Access Journals (Sweden)

    Rogerio Stojanov Bueno

    2009-12-01

    Full Text Available This experiment was developed at the marine farm of the São Paulo State Fisheries Institute in Ubatuba, SP, Brazil, aiming to compare the efficiency of three organisms (the sea urchins Echinometra lucunter, Lytechinus variegatus and the gastropod Tegula viridula in controlling fouling incrustation in lantern net and on Nodipecten nodosus valves. Scallops measuring 32.6 + 4.9mm of initial height were cultivated in eight Japanese lanterns with five floors each, at a density of 25 scallops/floor, according to the following delineament: T1 – control (scallops alone; T2 – scallops with E. lucunter; T3 – scallops with L. variegatus; T4 – scallops with T. viridula. Densities of the bio-controllers were: four (E. lucunter, three (L. variegatus and 15 animals/floor (T. viridula. The experiment was finished 150 days later and the remaining fouling in the lanterns and on the scallops valves was removed and weighed (dry weights. The sea-urchin species E. lucunter and L. variegatus were significantly more efficient in removing the lantern fouling (86% and 59% relative to the control treatment respectively, but there were no significant differences among the biocontrollers in controlling the fouling on the scallop valves. These results suggest that biological control can be helpful as an auxiliary method in scallop culture fouling removal.

  4. Anti-fouling Coatings of Poly(dimethylsiloxane) Devices for Biological and Biomedical Applications.

    Science.gov (United States)

    Zhang, Hongbin; Chiao, Mu

    Fouling initiated by nonspecific protein adsorption is a great challenge in biomedical applications, including biosensors, bioanalytical devices, and implants. Poly(dimethylsiloxane) (PDMS), a popular material with many attractive properties for device fabrication in the biomedical field, suffers serious fouling problems from protein adsorption due to its hydrophobic nature, which limits the practical use of PDMS-based devices. Effort has been made to develop biocompatible materials for anti-fouling coatings of PDMS. In this review, typical nonfouling materials for PDMS coatings are introduced and the associated basic anti-fouling mechanisms, including the steric repulsion mechanism and the hydration layer mechanism, are described. Understanding the relationships between the characteristics of coating materials and the accompanying anti-fouling mechanisms is critical for preparing PDMS coatings with desirable anti-fouling properties.

  5. Combining Coagulation/MIEX with Biological Activated Carbon Treatment to Control Organic Fouling in the Microfiltration of Secondary Effluent.

    Science.gov (United States)

    Pramanik, Biplob Kumar; Roddick, Felicity A; Fan, Linhua

    2016-07-30

    Coagulation, magnetic ion exchange resin (MIEX) and biological activated carbon (BAC) were examined at lab scale as standalone, and sequential pre-treatments for controlling the organic fouling of a microfiltration membrane by biologically treated secondary effluent (BTSE) using a multi-cycle approach. MIEX gave slightly greater enhancement in flux than coagulation due to greater removal of high molecular weight (MW) humic substances, although it was unable to remove high MW biopolymers. BAC treatment was considerably more effective for improving the flux than coagulation or MIEX. This was due to the biodegradation of biopolymers and/or their adsorption by the biofilm, and adsorption of humic substances by the activated carbon, as indicated by size exclusion chromatography. Coagulation or MIEX followed by BAC treatment further reduced the problematic foulants and significantly improved the flux performance. The unified membrane fouling index showed that the reduction of membrane fouling by standalone BAC treatment was 42%. This improved to 65%, 70%, and 93% for alum, ferric chloride and MIEX pre-treatment, respectively, when followed by BAC treatment. This study showed the potential of sequential MIEX and BAC pre-treatment for controlling organic fouling and thus enhancing the performance of microfiltration in the reclamation of BTSE.

  6. Understanding the fouling of UF/MF hollow fibres of biologically treated wastewaters using advanced EfOM characterization and statistical tools

    KAUST Repository

    Filloux, Emmanuelle

    2012-08-01

    Five secondary effluents and a river water source were characterized using size exclusion chromatography (LC-OCD-UVD-OND) and emission-excitation matrix (EEM) fluorescence spectroscopy in order to identify the major effluent organic matter (EfOM) fractions responsible for membrane fouling. This study showed the feasibility of coupling fluorescence EEM and LC-OCD-UVD-OND to investigate the fouling potential as well as a means to differentiate natural organic matter (NOM) from EfOM. The secondary effluents and river water showed a significant difference in organic matter characteristics and fouling potential, highlighting the importance of biological processes and the feed water source on EfOM characteristics and fouling potential. On the basis of statistical analysis, protein-like substances were found to be highly correlated to the fouling potential of secondary effluents. © 2012 Elsevier Ltd.

  7. Anti-fouling Coatings of Poly(dimethylsiloxane) Devices for Biological and Biomedical Applications

    OpenAIRE

    Zhang, Hongbin; Chiao, Mu

    2015-01-01

    Fouling initiated by nonspecific protein adsorption is a great challenge in biomedical applications, including biosensors, bioanalytical devices, and implants. Poly(dimethylsiloxane) (PDMS), a popular material with many attractive properties for device fabrication in the biomedical field, suffers serious fouling problems from protein adsorption due to its hydrophobic nature, which limits the practical use of PDMS-based devices. Effort has been made to develop biocompatible materials for anti-...

  8. Long-term operation of biological activated carbon pre-treatment for microfiltration of secondary effluent: Correlation between the organic foulants and fouling potential.

    Science.gov (United States)

    Pramanik, Biplob Kumar; Roddick, Felicity A; Fan, Linhua

    2016-03-01

    The impact of long-term (>2 years) biological activated carbon (BAC) treatment for mitigating organic fouling in the microfiltration of biologically treated secondary effluent was investigated. Correlation between the organic constituents and hydraulic filtration resistance was investigated to identify the major components responsible for fouling. Over two years operation, the removal efficiency for dissolved organic carbon (DOC) by the BAC treatment was fairly consistent (30 ± 3%), although the reduction in UVA254 gradually decreased from 56 to 34%. BAC treatment effectively decreased the organic foulants in the effluent and so contributed to the mitigation of membrane fouling as shown by reduction in the unified membrane fouling index (UMFI). BAC consistently removed biopolymers whereas the removal of humic substances decreased from 52 to 25% after two years of BAC operation, and thus led to a gradual decrease in UMFI reduction efficiency from 78 to 43%. This was due to gradual reduction in adsorption capacity of the activated carbon as confirmed by analysis of its pore size distribution. Hence humics also played an important role in membrane fouling. However, there was a good correlation between protein and carbohydrate contents with hydraulically reversible and irreversible filtration resistance, compared with UVA254, turbidity and DOC. Although the mitigation of membrane fouling decreased over time, this study demonstrated that the long-term use of BAC pre-treatment of biologically treated secondary effluent prior to microfiltration has potential to reduce the need for frequent chemical cleaning and so increase membrane life span.

  9. Separation, Characterization and Fouling Potential of Sludge Waters from Different Biological Wastewater Treatment Processes

    KAUST Repository

    Xue, Jinkai

    2011-07-01

    The major limitation, which hinders the wider application of membrane technology and increases the operating costs of membranes involved in wastewater treatment plants, is membrane fouling induced by organic matter. Extracellular polymeric products (EPS) and soluble microbial products (SMP) are the two most mentioned major foulants in publications, for which the debate on precise definitions seems to be endless. Therefore, a concept of sludge water, which conceptually covers both EPS and SMP, has been developed in this research. A standard procedure of sludge water separation, which is centrifugation at 4000g for 15 min followed by 1.2μm glass fiber filter filtration, was established based on separation experiments with membrane tank sludge from the KAUST MBR wastewater treatment plant. Afterwards, sludge waters from the KAUST MBR WWTP anoxic tank, aerobic tank and membrane tank as well as sludge waters from the Jeddah WWTP anoxic tank, aerobic tank and secondary effluent were produced through the previously developed standard procedure. The obtained sludge water samples were thereafter characterized with TOC/COD, LC-­‐OCD and F-­‐EEM, which showed that KAUST anoxic/ aerobic /membrane tank sludge waters had similar characteristics for all investigated parameters, yet the influent naturally had a higher DOC and biopolymer concentration. Moreover, lower TOC/COD, negligible biopolymers and low levels of humics were found in KAUST effluent. Compared with the KAUST MBR WWTP, the Jeddah WWTP’s sludge waters generally had higher DOC and biopolymer concentrations. To investigate sludge water fouling potential, the KAUST membrane tank sludge water as well as the Jeddah secondary effluent were filtrated through a membrane array consisting of an ultrafiltration (UF) Millipore RC10kDa at the first step followed by a nanofiltration (NF) KOCH Acid/Base stable NF200 at the second step. It was found that cake layer and standard blocking occurred simultaneously during both

  10. A STUDY OF MARINE FOULING IN MONTEREY HARBOR.

    Science.gov (United States)

    PIERS, *FOULING, *HARBORS, *MARINE BIOLOGY, CALIFORNIA, PACIFIC OCEAN, NAVAL RESEARCH, CRUSTACEA, ANIMALS, PERIODIC VARIATIONS, ENVIRONMENTAL TESTS, TIME, DISTRIBUTION, SEA WATER, PLATYHELMINTHES , OCEANOGRAPHIC DATA.

  11. Studies on the Biology of the Tube-Building Amphipod Microdeutopus gryllotalpa. A Model for Marine Fouling Processes.

    Science.gov (United States)

    1984-01-01

    available the facilities neceary to perform this work. I males’ travels, also thank R. Borowsky for a critical review of the -[This does not rule out the...1982. Larval morphology and diversity. Pages 43-110 in D. Bliss, ed. Biology of the crustacea, Vol. II. Embryology , morphology and genetics. Academic

  12. Seasonal variations in fouling diatom communities on the Yantai coast

    Science.gov (United States)

    Yang, Cuiyun; Wang, Jianhua; Yu, Yang; Liu, Sujing; Xia, Chuanhai

    2015-03-01

    Fouling diatoms are a main component of biofilm, and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater, on the Yantai coast, northern Yellow Sea, China, using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3, 7, 14, and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca, Nitzschia, Navicula, Amphora, Gomphonema, and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions, we found that Cylindrotheca grew very fast, which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.

  13. New method for control of biological fouling in pipelines based on elevated partial pressures of carbon dioxide or combustion exhaust gases.

    Energy Technology Data Exchange (ETDEWEB)

    B.J. Watten; R.E. Sears; R.F. Bumgardner [U.S. Geological Survey - Leetown Science Center, Kearneysville, WV (United States)

    2005-07-01

    Zebra mussels (Dreissena polymorpha) and Asian clams (Corbicula fluminea) are major macro fouling species of water conduits used in industrial and power station raw water/condensor systems. Control typically involves manual scraping and use of thermal treatment, deoxygenation or biocides. The costs of control and system damage resulting from fouling in the United States alone have been estimated at $1 billion/year. There is a pressing need for new economical and safe control strategies. Aquatic species in general are intolerant to increases in PCO{sub 2} given its effect on water, blood and hemolymph pH. These species are also sensitive to increases in elevated total dissolved gas pressure. The gas bubble disease that develops following exposure can, as with CO{sub 2} exposure, lead to mortality. We are exploiting this sensitivity by developing a control method based on manipulation of PCO{sub 2} or power plant exhaust gas (CO{sub 2}, 14%; SO{sub 2}, 0.3%), i.e., the supersaturation of hemolymph and tissues with gas followed by an induced (short term) pressure release designed to induce formation of gas emboli. SO{sub 2} present in stack gas acts with CO{sub 2} to reduce water and hemolymph pH so as to reduce required exposure periods. System effluents are degassed, CO{sub 2} recovered and pH adjusted if needed with alkaline reagents. Test results indicate the new process is effective at controlling C. fluminea as well as other target species, including crustaceans and fish. Required exposure periods (LT50) are short and decrease with increasing gas supersaturation levels. Gas recovery and reuse methods developed have reduced gas requirements by 85% making the method attractive economically and environmentally. 40 refs., 8 figs., 1 tab.

  14. Mixed salt crystallisation fouling

    CERN Document Server

    Helalizadeh, A

    2002-01-01

    The main purpose of this investigation was to study the mechanisms of mixed salt crystallisation fouling on heat transfer surfaces during convective heat transfer and sub-cooled flow boiling conditions. To-date no investigations on the effects of operating parameters on the deposition of mixtures of calcium sulphate and calcium carbonate, which are the most common constituents of scales formed on heat transfer surfaces, have been reported. As part of this research project, a substantial number of experiments were performed to determine the mechanisms controlling deposition. Fluid velocity, heat flux, surface and bulk temperatures, concentration of the solution, ionic strength, pressure and heat transfer surface material were varied systematically. After clarification of the effect of these parameters on the deposition process, the results of these experiments were used to develop a mechanistic model for prediction of fouling resistances, caused by crystallisation of mixed salts, under convective heat transfer...

  15. Milk fouling in heat exchangers.

    NARCIS (Netherlands)

    Jeurnink, Th.J.M.

    1996-01-01

    The mechanisms of fouling of heat exchangers by milk were studied. Two major fouling mechanisms were indentified during the heat treatment of milk: (i) the formation and the subsequent deposition of activated serum protein molecules as a result of the heat denaturation; (ii) the precipitation of cal

  16. Dirty air conditioners: Energy implications of coil fouling

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Jeffrey; Walker, Iain; Sherman, Max

    2002-03-01

    Residential air conditioning is responsible for a substantial amount of peak electrical demand and energy consumption throughout most of the United States. Coil fouling, the deposition of indoor dusts and other particulate matter on evaporator heat exchangers, increases system pressure drop and, correspondingly, decreases system air flow and air conditioner performance. In this paper, we apply experimental and simulation results describing particle deposition on evaporator coils as well as research about indoor particle and dust concentrations to determine coil fouling rates. The results suggest that typical coils foul enough to double evaporator pressure drop in about 7.5 years, much sooner than the expected 15-30 year life time for an evaporator coil. The most important parameters in determining coil fouling times are the efficiency of the filter and indoor particle concentrations, although filter bypass and duct and coil design are important as well. The reduced air flows that result from coil fouling cause typical efficiency and capacity degradations of less than 5%, however they can be much greater for marginal systems or extreme conditions. These energy issues, as well as possible indoor air quality issues resulting from fouling by biological aerosols, suggest that regular coil cleaning to ameliorate low flow and the elimination of filter bypass should be an important part of residential air conditioning commissioning and maintenance practices.

  17. Engineering factors influencing Corbicula fouling in nuclear-service water systems

    Energy Technology Data Exchange (ETDEWEB)

    Henager, C.H.; Johnson, K.I.; Page, T.L.

    1983-06-01

    Corbicula fouling is a continuing problem in nuclear-service water systems. More knowledge of biological and engineering factors is needed to develop effective detection and control methods. A data base on Corbicula fouling was compiled from nuclear and non-nuclear power stations and industries using raw water. This data base was used in an analysis to identify systems and components which are conducive to fouling by Corbicula. Bounds on several engineering parameters such as velocity and temperature which support Corbicula growth are given. Service water systems found in BWR and PWR reactors are listed and those that show fouling are identified. Possible safety implications of Corbicula fouling are discussed for specific service water systems. Several effective control methods in current use include backflushing with heated water, centrifugal strainers, and continuous chlorination during spawning seasons.

  18. Fuel sulfur and boiler fouling

    Energy Technology Data Exchange (ETDEWEB)

    Litzke, W.; Celebi, Y.; Butcher, T. [Brookhaven National Lab., Upton, NY (United States)

    1995-04-01

    Fouling of the heat transfer surfaces of boilers and furnaces by `soot` leads to reduced efficiency and increased service requirements. The average level of annual efficiency reduction as a result of fouling if generally accepted as 2% per year. Improving the efficiency of equipment in the field may be the most important oil heat conservation opportunity at present. Improvements can be realized by reducing fouling rates, promoting lower firing rates in existing equipment, and enabling excess air levels to be set lower without raising concerns about increased service requirements. In spite of the importance of efficiency in the field there is very little data available on efficiency degradation rates with modern equipment, actual field operating conditions (excess air and smoke number settings) and service problems which affect efficiency. During 1993-94 field tests were initiated to obtain such data and to obtain information that would compliment existing and current laboratory work. Experimental work conducted on a bench scale level have included tests with various advanced burners, fuel types, and different operating conditions which have been done at the BNL Rapid Fouling Test Facility. This report will focus on the field study of fouling effects on ten residential heating service problems at each site are summarized. In addition, the technical difficulties involved with conducting such a field study shall also be discussed as the findings should serve to improve future work in this area.

  19. 49 CFR 214.323 - Foul time.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Foul time. 214.323 Section 214.323 Transportation... TRANSPORTATION RAILROAD WORKPLACE SAFETY Roadway Worker Protection § 214.323 Foul time. Working limits established on controlled track through the use of foul time procedures shall comply with the...

  20. Probe Measures Fouling As In Heat Exchangers

    Science.gov (United States)

    Marner, Wilbur J.; Macdavid, Kenton S.

    1990-01-01

    Combustion deposits reduce transfer of heat. Instrument measures fouling like that on gas side of heat exchanger in direct-fired boiler or heat-recovery system. Heat-flux probe includes tube with embedded meter in outer shell. Combustion gases flow over probe, and fouling accumulates on it, just as fouling would on heat exchanger. Embedded heat-flow meter is sandwich structure in which thin Chromel layers and middle alloy form thermopile. Users determine when fouling approaches unacceptable levels so they schedule cleaning and avoid decreased transfer of heat and increased drop in pressure fouling causes. Avoids cost of premature, unnecessary maintenance.

  1. Fouling control in seawater by on-line acid addition

    Energy Technology Data Exchange (ETDEWEB)

    Salvago, G.; Taccani, G.; Polimeni, R. [ITM-CNR, Milano (Italy); Fumagalli, G.; Picenoni, D. [CNR-CESPEL Politecnico di Milano (Italy)

    1996-11-01

    An experimental plant was set up containing once-through test lines supplied with seawater. The pH level of the seawater was maintained at 6.3 by the acids addition. Heat exchange monitoring equipment and channels exposing different metal specimens were installed on each of the lines. Observation by microscope and EDS analyses were carried out both on the specimen surfaces and on the cross section of the fouling after fracturing in liquid N{sub 2}. The results obtained show that: fouling must not be confused with its effects or simply with its biological components; acidifying seawater can prevent the resistance to heat exchange from increasing without impeding its biological activity. Observation by microscope of the fouling cross sections showed that in untreated seawater the foulings on stainless steel were composed of a continuous compact layer, covered by disorderly clusters. These compact layers were found to contain high quantities of corrosion products of the metals. Elements typical of corrosion products of ferrous materials (Fe, Mn) were also found on Pt, copper alloys and plastic materials. The addition of HCl or H{sub 2}SO{sub 4} to the seawater, to bring it to pH 6.3, reduces the amount of fouling adhering to the surfaces, prevents the development of the continuous layer containing iron and prevents significant increases in heat exchange resistance. The addition of CO{sub 2} can encourage the development of incoherent fibrous material with high Si content and low Fe content which is of little impediment to heat exchange. The addition of lactic acid can encourage both the abnormal development of biomass and the formation of several, separate, layers on stainless steel surfaces.

  2. Anti-fouling bioactive surfaces.

    Science.gov (United States)

    Yu, Qian; Zhang, Yanxia; Wang, Hongwei; Brash, John; Chen, Hong

    2011-04-01

    Bioactive surfaces refer to surfaces with immobilized bioactive molecules aimed specifically at promoting or supporting particular interactions. Such surfaces are of great importance for various biomedical and biomaterials applications. In the past few years, considerable effort has been made to create bioactive surfaces by forming specific biomolecule-modified surfaces on a non-biofouling "base" or "background". Hydrophilic and bioinert polymers have been widely used as anti-fouling layers that resist non-specific protein interactions. They can also serve as "spacers" to effectively move the immobilized biomolecule away from the surface, thus enhancing its bioactivity. In this review we summarize several successful approaches for the design and preparation of bioactive surfaces based on different types of anti-fouling/spacer materials. Some perspectives on future research in this area are also presented.

  3. The Modified Fouling Index Ultrafiltration constant flux for assessing particulate/colloidal fouling of RO systems

    NARCIS (Netherlands)

    Salinas-Rodriguez, S.G.; Amy, G.L.; Schippers, J.C.; Kennedy, M.D.

    2015-01-01

    Reliable methods for measuring and predicting the fouling potential of reverse osmosis (RO) feed water are important in preventing and diagnosing fouling at the design stage, and for monitoring pre-treatment performance during plant operation. The Modified Fouling Index Ultrafiltration (MFI-UF) cons

  4. Investigation into fouling factor in compact heat exchanger

    OpenAIRE

    Masoud Asadi; Ramin Haghighi Khoshkhoo

    2013-01-01

    Fouling problems cannot be avoided in many heat exchanger operations, and it is necessary to introduce defensive measures to minimize fouling and the cost of cleaning. The fouling control measures used during either design or operation must be subjected to a thorough economic analysis, taking into consideration all the costs of the fouling control measures and their projected benefits in reducing costs due to fouling. Under some conditions, nearly asymptotic fouling resistances can be obtaine...

  5. Offshore fouling:investigation methods

    Institute of Scientific and Technical Information of China (English)

    YAN Tao; YAN Wenxia; DONG Yu; LIANG Guanhe; YAN Yan; WANG Huajie

    2004-01-01

    On the hasis of the reason that the offshore oil development areas in the northern South China Sea are at greater depth,more hazardous conditions and distance from shore, the methods and technologies used in coastal waters are not feasible because of the higher risk of losing investigation equipment or facilities. A series of methods and technologies for offshore fouling investigation that have been successfully applied is given in detail and it is hoped that the experience can be helpful for further studies.

  6. Reliability Based Management of Marine Fouling

    DEFF Research Database (Denmark)

    Faber, Michael Havbro; Hansen, Peter Friis

    1999-01-01

    of uncertainties of a set of parameters. These are the seasonal variation of marine fouling parameters, the wave loading (taking into account the seasonal variation in sea-state statistics), and the effects of spatial variations and seasonal effects of marine fouling parameters. Comparison of design values...... obtained by the present model taking into account seasonal effects with those inherent in the current design specifications are made and criteria are formulated for removal of marine fouling taking into account seasonal differences in marine fouling. A methodology is outlined on how to establish new......The present paper describes the results of a recent study on the application of methods from structural reliability to optimise management of marine fouling on jacket type structures.In particular the study addresses effects on the structural response by assessment and quantification...

  7. New biocide-free anti-fouling paints are toxic.

    Science.gov (United States)

    Karlsson, Jenny; Eklund, Britta

    2004-09-01

    A number of new anti-fouling paints claimed to be more friendly to the environment, have entered the market since prohibition of biocide containing paints have been enforced in many areas. Leakage waters from five new anti-fouling paints were tested for toxic effects to the macro algae Ceramium tenuicorne and Ceramium strictum and to the crustacean Nitocra spinipes. A banned copper and irgarol 1051 containing anti-fouling paint was used as reference. Five of the six paints tested were toxic to all or some of the organisms after two weeks of leakage with EC50 ranging from 0.08 to around 2% leakage water and LC50 ranging from 1.1% to 88%. The toxicity of leakage water from these paints was still high after 16 weeks. We conclude that these paints contain substances toxic to common organisms in the coastal Baltic ecosystem. A silicone based paint did not exhibit toxic effects to the two organisms. We recommend that biological tests should be used to identify the most harmful products before they are released on the market.

  8. Fouling distribution in forward osmosis membrane process.

    Science.gov (United States)

    Lee, Junseok; Kim, Bongchul; Hong, Seungkwan

    2014-06-01

    Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis (FO) membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic (alginate) fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter-current flow operation of FO membrane process.

  9. Effect study on a biological prevention method applying mix-culturing of saltmarsh and Avicennia marina mangrove trees to reduce marine fouling fauna damage%盐沼草--白骨壤混种减轻污损动物危害的生物防治效果研究

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    In Beilun estuarine area of Guangxi,China,the intertidal flat were filled to an elevation of about 220 cm Yellow Sea Datum to mix-culture Avicennia marina (AM)seedlings with four species of saltmarsh,aimed at stud-ying the effect of biological prevention method for reducing the fouling damage on mangrove trees.The results showed that Cyperus malaccensis (CM)and Zoysia matrella (ZM)were able to grow and spread faster,and more ef-ficient to slow down water velocity and accelerate sedimentation than Scirpus validus var.laeviglumis (SV)and Phragmites australis (PA).19 species of fouling fauna were found on saltmarsh and mangroves,among which Bala-nus littoralis ,Euraphia withersi ,Littorina melanostoma and L .scabra were major dominant species.Among four saltmarsh species,the fouled degrees on CM and ZM were significantly less than those on other two species.And the fouled degrees on four saltmarsh species were all significantly less than that on A .marina tree.The mix-culturing of saltmarsh CM or ZM with mangrove tree AM could efficiently reduce the fouling damage,resulting in better tree growth indexes i.e.tree height,leaf number,branch number,branch conservation and survival rate than those in mono-species treatment areas.In general,a saltmarsh-mangrove cooperating ecological conservation system could be a practical model for mangrove afforestation.%广西北仑河口区新造高程约220 cm 的潮间带裸滩,移植白骨壤与茳芏、沟叶结缕草、芦苇和南水葱四种盐沼草进行混种,研究盐沼草-红树混种减轻污损动物对人工红树林危害的生物防治效果。结果表明:沟叶结缕草和茳芏可快速生长和扩展,缓流、促淤能力高于长势较差的南水葱和芦苇。在盐沼和白骨壤上发现19种污损动物,其中潮间藤壶、白条地藤壶、黑口滨螺和粗糙滨螺为优势种。茳芏和沟叶结缕草受污损程度较南水葱和芦苇轻。四种盐沼草受污损程度均低于白骨壤

  10. Fouling and Antifouling of Depetanizer in Ethylene Units

    Institute of Scientific and Technical Information of China (English)

    Dong Zhongjie; Li Yunlong; Fan Xuezhi; Hong Qingyao

    2002-01-01

    Factors affecting fouling of depentanizer in ethylene units wereexplored through study of thecomposition of pyrolysis gasoline, C5 distillate and fouling deposits from the depentanizer while takinginto consideration the processing parameters. A variety of antifouling measures, in particular the injec-tion of a special anti-fouling agent into the Cs gas phase pipeline and the C5 distillate reflux pipelinewere introduced. Commercial evaluation test of a multifunctional anti-fouling agent, the RIPP-1404anti-fouling agent, was also described.

  11. Microbial Relevant Fouling in Membrane Bioreactors: Influencing Factors, Characterization, and Fouling Control

    OpenAIRE

    Anthony G. Fane; Bing Wu

    2012-01-01

    Microorganisms in membrane bioreactors (MBRs) play important roles on degradation of organic/inorganic substances in wastewaters, while microbial deposition/growth and microbial product accumulation on membranes potentially induce membrane fouling. Generally, there is a need to characterize membrane foulants and to determine their relations to the evolution of membrane fouling in order to identify a suitable fouling control approach in MBRs. This review summarized the factors in MBRs that inf...

  12. Amphiphilic copolymers for fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, Stefan Møller; Hvilsted, Søren

    Polydimethylsiloxane (PDMS) resins are extensively used as binder in fouling-release coatings due to the low critical surface energy and low elastic modulus of PDMS. These properties result in poor adhesion of the fouling organisms, which are therefore detached by hydrodynamic forces during...... navigation [1,2,3]. Other compounds are usually mixed together with the binder (e.g. silica and pigments) in order to improve the mechanical, thixotropic and visual properties of the coatings. It has ben shown, however, that these ingredients have a negative effect on the fouling-release properties...... of the coatings [1,2,4]. Together with the PDMS-system, non-reactive polymers have been used to improve the fouling-release properties of the coatings. Initially, hydrophobic siloxane-based polymers were used, which aimed to increase the hydrophobicity of the PDMS surface [5,6]. However, copolymers comprising...

  13. Amphiphilic copolymers for fouling-release coatings

    OpenAIRE

    Noguer, Albert Camós; Olsen, Stefan Møller; Hvilsted, Søren; Kiil, Søren

    2016-01-01

    Polydimethylsiloxane (PDMS) resins are extensively used as binder in fouling-release coatings due to the low critical surface energy and low elastic modulus of PDMS. These properties result in poor adhesion of the fouling organisms, which are therefore detached by hydrodynamic forces during navigation [1,2,3]. Other compounds are usually mixed together with the binder (e.g. silica and pigments) in order to improve the mechanical, thixotropic and visual properties of the coatings. It has ben s...

  14. Effects of salinity on the characteristics of biomass and membrane fouling in membrane bioreactors

    DEFF Research Database (Denmark)

    Jang, D.; Hwang, Yuhoon; Shin, H.

    2013-01-01

    This study investigated the effects of high salinity on the performance and membrane fouling of membrane bioreactor (MBR) with saline wastewater. Synthetic wastewaters containing 5-20g/L salts (NaCl) were treated in identical lab-scale (7L) MBRs monitoring removals of dissolved organic carbon (DOC......; and the changes in microbial composition in turn have affected the performance of the MBRs. Membrane fouling was accelerated by the increased pore blocking resistance at higher salt concentrations. Analysis results of physicochemical and biological characteristics of biomass (EPS, floc size, zeta potential...

  15. Prevention of PVDF ultrafiltration membrane fouling by coating MnO2 nanoparticles with ozonation

    Science.gov (United States)

    Yu, Wenzheng; Brown, Matthew; Graham, Nigel. J. D.

    2016-07-01

    Pre-treatment is normally required to reduce or control the fouling of ultrafiltration (UF) membranes in drinking water treatment process. Current pre-treatment methods, such as coagulation, are only partially effective to prevent long-term fouling. Since biological activities are a major contributor to accumulated fouling, the application of an oxidation/disinfection step can be an effective complement to coagulation. In this study, a novel pre-treatment method has been evaluated at laboratory scale consisting of the addition of low dose ozone into the UF membrane tank after coagulation and the use of a hollow-fibre membrane coated with/without MnO2 nanoparticles over a test period of 70 days. The results showed that there was minimal fouling of the MnO2 coated membrane (0.5 kPa for 70 days), while the uncoated membrane experienced both reversible and irreversible fouling. The difference was attributed to the greatly reduced presence of bacteria and organic matter because of the catalytic decomposition of ozone to hydroxyl radicals and increase of the hydrophilicity of the membrane surface. In particular, the MnO2 coated membrane had a much thinner cake layer, with significantly less polysaccharides and proteins, and much less accumulated organic matter within the membrane pores.

  16. Increased algal fouling on mussels with barnacle epibionts: a fouling cascade

    Science.gov (United States)

    Gutiérrez, Jorge L.; Palomo, M. Gabriela

    2016-06-01

    If the external surfaces of epibionts are more suitable to other fouling species than those of their basibionts, a 'fouling cascade' might occur where epibionts facilitate secondary colonization by other epibionts. Here we evaluate whether the presence of epibiotic barnalces (Balanus glandula) influences the probability of mussel (Brachidontes rodriguezii) fouling by ephemeral red algae (Porphyra sp.) in a Southwestern Atlantic rocky shore. Mussels with barnacle epibionts showed a higher prevalence of Porphyra sp. fouling (32-40% depending on sampling date) than mussels without them (3-7%). Two lines of evidence indicate that barnacles facilitate Porphyra sp. fouling. First, most Porphyra sp. thalli in mussels with barnacle epibionts were attached to barnacle shells (75-92% of cases). Secondly, Porphyra sp. associated with mussels with barnacle epibionts in a proportion that significantly exceeded that expected under random co-occurrence. These results suggest the occurrence of a fouling cascade where barnacle epibiosis on mussels facilitates subsequent algal fouling. Recognizing the occurrence of such fouling cascades is important because they might explain the non-random aggregation of multiple epibiotic species onto a proportionally few individuals of the host species.

  17. Fouling in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    Yan Tao; Yan Wenxia; Dong Yu; Liang Guanhe; Yan Yan; Wang Huajie

    2003-01-01

    In order to understand the type and extent of marine fouling in offshore areas southeast of the Zhujiang (Pearl) River delta, within the period form May 1986 to June 1987, two biological buoys were deployed at water depths of 95 m and 113 m located in 114 km and 160 km off the coast of Hong Kong, respectively. Moreover, the fouling community of a Marex hydrological buoy located in 115 m depth water 172 km off Hong Kong was also surveyed. The results show that a total of 78 species were collected and identified. The panels exposed for 3 months were mainly dominated by stalked barnacles Conchoderma hunteri and Lepas anatifera and hydroids Orthopyxis sp. As for the buoys, including the subsurface buoy, and their mooring systems exposed for 6 and 12 months, respectively, some hard foulers such as common oysters, pearl oysters, acorn barnacles and bryozoans were also found. The compositions of fouling communities also varied greatly with depth.

  18. High-temperature organic-fluid fouling unit

    Energy Technology Data Exchange (ETDEWEB)

    Kuru, W.C.; Panchal, C.B.

    1997-06-01

    A new type of fouling unit is developed for high-temperature (500 C) and high-pressure (70 atmosphere) fouling experiments by modifying a commercial autoclave. Key modifications are the installation of a helical impeller in a flow tube and a fouling probe in the autoclave to simulate the fluid dynamics and heat transfer of typical heat-exchange equipment. A calibration technique is described, and fouling results are presented for experimental runs with indene and kerosene. The results are compared with those obtained using other types of fouling test units. Other potential applications of the fouling unit, such as corrosion and micro-scale reaction experiments, are discussed.

  19. Drag of Clean and Fouled Net Panels--Measurements and Parameterization of Fouling.

    Directory of Open Access Journals (Sweden)

    Lars Christian Gansel

    Full Text Available Biofouling is a serious problem in marine aquaculture and it has a number of negative impacts including increased forces on aquaculture structures and reduced water exchange across nets. This in turn affects the behavior of fish cages in waves and currents and has an impact on the water volume and quality inside net pens. Even though these negative effects are acknowledged by the research community and governmental institutions, there is limited knowledge about fouling related effects on the flow past nets, and more detailed investigations distinguishing between different fouling types have been called for. This study evaluates the effect of hydroids, an important fouling organism in Norwegian aquaculture, on the forces acting on net panels. Drag forces on clean and fouled nets were measured in a flume tank, and net solidity including effect of fouling were determined using image analysis. The relationship between net solidity and drag was assessed, and it was found that a solidity increase due to hydroids caused less additional drag than a similar increase caused by change in clean net parameters. For solidities tested in this study, the difference in drag force increase could be as high as 43% between fouled and clean nets with same solidity. The relationship between solidity and drag force is well described by exponential functions for clean as well as for fouled nets. A method is proposed to parameterize the effect of fouling in terms of an increase in net solidity. This allows existing numerical methods developed for clean nets to be used to model the effects of biofouling on nets. Measurements with other types of fouling can be added to build a database on effects of the accumulation of different fouling organisms on aquaculture nets.

  20. Drag of Clean and Fouled Net Panels – Measurements and Parameterization of Fouling

    Science.gov (United States)

    Gansel, Lars Christian; Plew, David R.; Endresen, Per Christian; Olsen, Anna Ivanova; Misimi, Ekrem; Guenther, Jana; Jensen, Østen

    2015-01-01

    Biofouling is a serious problem in marine aquaculture and it has a number of negative impacts including increased forces on aquaculture structures and reduced water exchange across nets. This in turn affects the behavior of fish cages in waves and currents and has an impact on the water volume and quality inside net pens. Even though these negative effects are acknowledged by the research community and governmental institutions, there is limited knowledge about fouling related effects on the flow past nets, and more detailed investigations distinguishing between different fouling types have been called for. This study evaluates the effect of hydroids, an important fouling organism in Norwegian aquaculture, on the forces acting on net panels. Drag forces on clean and fouled nets were measured in a flume tank, and net solidity including effect of fouling were determined using image analysis. The relationship between net solidity and drag was assessed, and it was found that a solidity increase due to hydroids caused less additional drag than a similar increase caused by change in clean net parameters. For solidities tested in this study, the difference in drag force increase could be as high as 43% between fouled and clean nets with same solidity. The relationship between solidity and drag force is well described by exponential functions for clean as well as for fouled nets. A method is proposed to parameterize the effect of fouling in terms of an increase in net solidity. This allows existing numerical methods developed for clean nets to be used to model the effects of biofouling on nets. Measurements with other types of fouling can be added to build a database on effects of the accumulation of different fouling organisms on aquaculture nets. PMID:26151907

  1. Investigation of organic fouling of microfiltration membrane

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; CUI Chong-wei; MA Jun

    2005-01-01

    Because the natural organic matters (NOMs) and proteins are the principal foulants of microfiltration membranes in drinking water, the primary aim of this paper is to obtain a better understanding of the interactions between those foulants and the microfiltration membrane from a novel view of coagulation. Based on reviewed literature and our own analysis, the authors consider that the behaviors of NOMs in the fouling of microfiltration membrane are like a form of crystal growth, and we recognize that the extent of the membrane hydrophobicity plays an essential role in NOMs fouling. However, proteins' fouling is more affected by intermolecular interaction. Additionally, the effect of membrane surface chemistry is not as essential as it is in the situation of NOMs.

  2. Understanding membrane fouling mechanisms through computational simulations

    Science.gov (United States)

    Xiang, Yuan

    This dissertation focuses on a computational simulation study on the organic fouling mechanisms of reverse osmosis and nanofiltration (RO/NF) membranes, which have been widely used in industry for water purification. The research shows that through establishing a realistic computational model based on available experimental data, we are able to develop a deep understanding of membrane fouling mechanism. This knowledge is critical for providing a strategic plan for membrane experimental community and RO/NF industry for further improvements in membrane technology for water treatment. This dissertation focuses on three major research components (1) Development of the realistic molecular models, which could well represent the membrane surface properties; (2) Investigation of the interactions between the membrane surface and foulants by steered molecular dynamics simulations, in order to determine the major factors that contribute to surface fouling; and (3) Studies of the interactions between the surface-modified membranes (polyethylene glycol) to provide strategies for antifouling.

  3. 76 FR 76896 - International Anti-Fouling System Certificate

    Science.gov (United States)

    2011-12-09

    ... SECURITY Coast Guard 46 CFR Part 8 RIN 1625-AB79 International Anti-Fouling System Certificate AGENCY... regulations to add the International Anti-fouling System (IAFS) Certificate to the list of certificates a... Harmful Anti-fouling Systems on Ships, 2001. This final rule will enable recognized...

  4. 76 FR 54419 - International Anti-Fouling System Certificate

    Science.gov (United States)

    2011-09-01

    ... SECURITY Coast Guard 46 CFR Part 8 RIN 1625-AB79 International Anti-Fouling System Certificate AGENCY... vessel inspection regulations to add the International Anti-fouling System (IAFS) Certificate to the list... Convention on the Control of Harmful Anti-fouling Systems on Ships, 2001. This proposed rule would...

  5. Two-phase flow for fouling control in membranes

    NARCIS (Netherlands)

    Wibisono, Yusuf

    2014-01-01

    The real challenge of the use of NF/RO spiral-wound membrane modules in water treatment is membrane fouling. Fouling problems in NF/RO systems are more complicated than in low pressure membrane processes, becaused fouling usually occurs on the nanoscale, combined with the complex geometry of spiral-

  6. Fouling characteristics of compact heat exchangers and enhanced tubes.

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, C. B.; Rabas, T. J.

    1999-07-15

    Fouling is a complex phenomenon that (1) encompasses formation and transportation of precursors, and (2) attachment and possible removal of foulants. A basic understanding of fouling mechanisms should guide the development of effective mitigation techniques. The literature on fouling in complex flow passages of compact heat exchangers is limited; however, significant progress has been made with enhanced tubes.

  7. Review of hypotheses for fouling during beer clarification using membranes

    NARCIS (Netherlands)

    Mepschen, A.; Sman, van der R.G.M.; Vollebregt, H.M.; Noordman, T.R.

    2012-01-01

    Hypotheses concerning the fouling of membranes during beer clarification via crossflow microfiltration are reviewed. Beer has been classified into three groups of components, each having a different kind of fouling mechanisms – but also having interactions with other modes of fouling. The membrane f

  8. Fouling mechanisms of dairy streams during membrane distillation

    NARCIS (Netherlands)

    Hausmann, A.; Sanciolo, P.; Vasiljevic, T.; Weeks, M.; Schroën, C.G.P.H.; Gray, S.; Duke, M.

    2013-01-01

    This study reports on fouling mechanisms of skim milk and whey during membrane distillation (MD) using polytetrafluoroethylene (PTFE) membranes. Structural and elemental changes along the fouling layer from the anchorpoint at the membrane to the topsurface of the fouling layer have been investigated

  9. Performances and fouling control of a flat sheet membrane in a MBR pilot-plant.

    Science.gov (United States)

    Grélot, A; Grelier, P; Tazi-Pain, A; Lesjean, B; Brüss, U; Grasmick, A

    2010-01-01

    This paper deals with the performance and the optimisation of the hydraulic operating conditions of the A3 Water Solutions flat sheet membrane technology in a MBR pilot-plant to achieve a satisfying fouling control and also a reduction in the required aeration. Two vertically stacked modules were tested at pilot-scale at Anjou Recherche under typical biological operating conditions (mixed liquor suspended solids concentration (MLSS) =10 g/l; sludge retention time (SRT) =28 days; food to microorganism ratio (F/M)=0.12 kg COD/kg MLSS/d). The use of a double-deck and of specific backwashes for this membrane technology enabled to achieve satisfying membrane performances for a net flux of 25 L h(-1) m(-2), 20 degrees C at a low specific aeration demand per membrane surface (SADm = 0.2 Nm(3) h(-1) m(-2)) which corresponds to a specific aeration demand per permeate volume unit (SADp) of 8 Nm(3) air/m(3) permeate, which is lower than reported for many commercial membrane systems. The mixed liquor characteristics (foaming, MLSS concentration) appeared to influence the fouling behaviour of the membranes but no correlation was found with the fouling rate. However, with the new operating conditions, the system is robust and can cope with fouling resulting from biological stress and daily peak flows for MLSS concentrations in the membrane tank up to 18 g/l.

  10. Influence of Chlorination and Choice of Materials on Fouling in Cooling Water System under Brackish Seawater Conditions

    Directory of Open Access Journals (Sweden)

    Pauliina Rajala

    2016-06-01

    Full Text Available Cooling systems remove heat from components and industrial equipment. Water cooling, employing natural waters, is typically used for cooling large industrial facilities, such as power plants, factories or refineries. Due to moderate temperatures, cooling water cycles are susceptible to biofouling, inorganic fouling and scaling, which may reduce heat transfer and enhance corrosion. Hypochlorite treatment or antifouling coatings are used to prevent biological fouling in these systems. In this research, we examine biofouling and materials’ degradation in a brackish seawater environment using a range of test materials, both uncoated and coated. The fouling and corrosion resistance of titanium alloy (Ti-6Al-4V, super austenitic stainless steel (254SMO and epoxy-coated carbon steel (Intershield Inerta160 were studied in the absence and presence of hypochlorite. Our results demonstrate that biological fouling is intensive in cooling systems using brackish seawater in sub-arctic areas. The microfouling comprised a vast diversity of bacteria, archaea, fungi, algae and protozoa. Chlorination was effective against biological fouling: up to a 10–1000-fold decrease in bacterial and archaeal numbers was detected. Chlorination also changed the diversity of the biofilm-forming community. Nevertheless, our results also suggest that chlorination enhances cracking of the epoxy coating.

  11. Fouling and Antifouling of Depetanizer in Ethylene Units

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Factors affecting fouling of depentanizer in ethylene units were explored through study of thecomposition of pyrolysis gasoline, C5 distillate and fouling deposits from the depentanizer while takinginto consideration the processing parameters. A variety of antifouling measures, in particular the injec-tion of a special anti-fouling agent into the Cs gas phase pipeline and the C5 distillate reflux pipelinewere introduced. Commercial evaluation test of a multifunctional anti-fouling agent, the RIPP-1404anti-fouling agent, was also described.

  12. Fouling and Antifouling of Depetanizer in Ethylene Units

    Institute of Scientific and Technical Information of China (English)

    DongZhongjie; LiYunlong; 等

    2002-01-01

    Factors affecting fouling of depentanizer in ethylene units were explored through study of the composition of pyrolysis gasoline,C5 distillate and fouling deposits from the depentanizer while taking into consideration the processing parameters.A variety of antifouling measures,in particular the injec-tion of a special anti-fouling agent into the C5 gas phase pipeline and the C5 distillate reflux pipeline were introduced.Commercial evaluation test of a multifunctional anti-fouling agent,the RIPP-1404 anti-fouling agent,was also described.

  13. CROSS-FLOW ULTRAFILTRATION OF SECONDARY EFFLUENTS. MEMBRANE FOULING ANALYSIS

    Directory of Open Access Journals (Sweden)

    Luisa Vera

    2014-12-01

    Full Text Available The application of cross-flow ultrafiltration to regenerate secondary effluents is limited by membrane fouling. This work analyzes the influence of the main operational parameters (transmembrane pressure and cross-flow velocity about the selectivity and fouling observed in an ultrafiltration tubular ceramic membrane. The experimental results have shown a significant retention of the microcolloidal and soluble organic matter (52 – 54% in the membrane. The fouling analysis has defined the critical operational conditions where the fouling resistance is minimized. Such conditions can be described in terms of a dimensionless number known as shear stress number and its relationship with other dimensionless parameter, the fouling number.

  14. Development of Low Fouling and High Fouling-release Zwitterionic Marine Coatings

    Science.gov (United States)

    2016-01-04

    NOTES 14. ABSTRACT This grant from ONR to Zwitter Technology, LLC is to develop, scale up and formulate a low-fouling and high-fouling-release marine...Transition progress or updates to plan 5 Program Objective This grant from ONR to Zwitter Technology, LLC is to develop, scale up and formulate a low...method to make block copolymers. Among several Controlled/Living radical polymerization techniques, Atom Transfer Radical Polymerization (ATRP) is most

  15. Fouled Anchors: The CONSTELLATION Question Answered

    Science.gov (United States)

    1991-09-01

    1711804 87AU 73 89-1-3401 11. TITLE (kcn e S.cE) Caut,.cawn) Fouled Anchors: The Constellation Question Answered IL. PERSONA .. AUTHOPS) Wegner, Dana M...was familia , with the unaltered Constellation in Newport and, unknown to the Committee, had indeed visited the ship once in Baltimore (see p. 45). It is

  16. Fouling corrosion in aluminum heat exchangers

    Directory of Open Access Journals (Sweden)

    Su Jingxin

    2015-06-01

    Full Text Available Fouling deposits on aluminum heat exchanger reduce the heat transfer efficiency and cause corrosion to the apparatus. This study focuses on the corrosive behavior of aluminum coupons covered with a layer of artificial fouling in a humid atmosphere by their weight loss, Tafel plots, electrochemical impedance spectroscopy (EIS, and scanning electron microscope (SEM observations. The results reveal that chloride is one of the major elements found in the fouling which damages the passive film and initiates corrosion. The galvanic corrosion between the metal and the adjacent carbon particles accelerates the corrosive process. Furthermore, the black carbon favors the moisture uptake, and gives the dissolved oxygen greater chance to migrate through the fouling layer and form a continuous diffusive path. The corrosion rate decreasing over time is conformed to electrochemistry measurements and can be verified by Faraday’s law. The EIS results indicate that the mechanism of corrosion can be interpreted by the pitting corrosion evolution mechanism, and that pitting was observed on the coupons by SEM after corrosive exposure.

  17. Fouling in reverse electrodialysis under natural conditions

    NARCIS (Netherlands)

    Vermaas, David A.; Kunteng, Damnearn; Saakes, Michel; Nijmeijer, Kitty

    2013-01-01

    Renewable energy can be generated from mixing salt water and fresh water in reverse electrodialysis. The potential for energy generation from mixing seawater and river water is enormous. To investigate the effect of fouling when such natural feed waters are used, the performance of three different s

  18. Characterization of fouling of membrane contactors

    DEFF Research Database (Denmark)

    Ciurkot, Kaludia; Zarebska, Agata; Christensen, Knud Villy

    2013-01-01

    achieved higher ammonia removal than the synthetic model manure solution. This might be due to the larger particle size of the milled straw in the model solution compared to the size of suspended solids present in real manure. From the fouling autopsy, it was found that PTFE membranes are more prone...

  19. The Modified Fouling Index Ultrafiltration constant flux for assessing particulate/colloidal fouling of RO systems

    KAUST Repository

    Salinas-Rodriguez, Sergio G.

    2015-02-18

    Reliable methods for measuring and predicting the fouling potential of reverse osmosis (RO) feed water are important in preventing and diagnosing fouling at the design stage, and for monitoring pre-treatment performance during plant operation. The Modified Fouling Index Ultrafiltration (MFI-UF) constant flux is a significant development with respect to assessing the fouling potential of RO feed water. This research investigates (1) the variables influencing the MFI-UF test at constant flux filtration (membrane pore size, membrane material, flux rate); and (2) the application of MFI-UF into pre-treatment assessment and RO fouling estimation. The dependency of MFI on flux, means that to assess accurately particulate fouling in RO systems, the MFI should be measured at a flux similar to a RO system (close to 20 L/m2/h) or extrapolated from higher fluxes. The two studied membrane materials showed reproducible results; 10% for PES membranes and 6.3% for RC membranes. Deposition factors (amount of particles that remain on the surface of membrane) were measured in a full-scale plant ranging between 0.2 and 0.5. The concept of “safe MFI” is presented as a guideline for assessing pre-treatment for RO systems.

  20. Protein antifouling and fouling-release in perfluoropolyether surfaces

    Science.gov (United States)

    Molena, Elena; Credi, Caterina; De Marco, Carmela; Levi, Marinella; Turri, Stefano; Simeone, Giovanni

    2014-08-01

    Perfluoropolyether polymers have been described as high performance fouling-release materials for marine coatings. Moreover, they have a good potential to be exploited in the biomedical field too. In this article several perfuoropolyether photopolymers were characterized in terms of surface and mechanical properties outlining the relationship between these properties and the polymer molecular structure. In particular the anti-fouling and fouling-release performances, evaluated using Bovine Serum Albumin as testing protein, was correlated to other material properties, like a parameter considering both surface tension components γ and elastic modulus E. A good correlation between the anti-fouling/fouling-release of perfluoropolyethers and (E*γpolar)1/2 can actually be established. Our results show that perfluoropolyether photopolymers are good protein anti-fouling/fouling-release materials.

  1. Mitigation of Syngas Cooler Plugging and Fouling

    Energy Technology Data Exchange (ETDEWEB)

    Bockelie, Michael J. [Reaction Engineering International, Salt Lake City, UT (United States)

    2015-06-29

    This Final Report summarizes research performed to develop a technology to mitigate the plugging and fouling that occurs in the syngas cooler used in many Integrated Gasification Combined Cycle (IGCC) plants. The syngas cooler is a firetube heat exchanger located downstream of the gasifier. It offers high thermal efficiency, but its’ reliability has generally been lower than other process equipment in the gasification island. The buildup of ash deposits that form on the fireside surfaces in the syngas cooler (i.e., fouling) lead to reduced equipment life and increased maintenance costs. Our approach to address this problem is that fouling of the syngas cooler cannot be eliminated, but it can be better managed. The research program was funded by DOE using two budget periods: Budget Period 1 (BP1) and Budget Period 2 (BP2). The project used a combination of laboratory scale experiments, analysis of syngas cooler deposits, modeling and guidance from industry to develop a better understanding of fouling mechanisms and to develop and evaluate strategies to mitigate syngas cooler fouling and thereby improve syngas cooler performance. The work effort in BP 1 and BP 2 focused on developing a better understanding of the mechanisms that lead to syngas cooler plugging and fouling and investigating promising concepts to mitigate syngas cooler plugging and fouling. The work effort focused on the following: • analysis of syngas cooler deposits and fuels provided by an IGCC plant collaborating with this project; • performing Jet cleaning tests in the University of Utah Laminar Entrained Flow Reactor to determine the bond strength between an ash deposit to a metal plate, as well as implementing planned equipment modifications to the University of Utah Laminar Entrained Flow Reactor and the one ton per day, pressurized Pilot Scale Gasifier; • performing Computational Fluid Dynamic modeling of industrially relevant syngas cooler configurations to develop a better

  2. Diesel injector fouling bench test methodology

    Science.gov (United States)

    Stavinoha, Leon L.; Yost, Douglas M.; Lestz, Sidney J.

    1992-06-01

    Compared to conventional compression ignition (CI) engine operation with the fuel being delivered at approximately 149 C (300 F), adiabatic engine operation potentially may deliver the fuel at temperatures as high as 260 C (500 F). Hypergolic CI engine combustion systems now in theoretical design stages will deliver fuel at temperatures approaching 427 to 538 C (800 to 1000 F). The ability of a fuel to resist formation of deposits on internal injector system surfaces is a form of thermal oxidative stability for which test methodology will be required. The injector Fouling Bench Test (IFBT) methodology evaluated in this report will assist in defining fuel contribution to injector fouling and control of fuel thermal stability in procurement specifications. The major observations from this project are discussed. Forty-hour cyclic IFB tests employing both Bosch APE 113 and Detroit Diesel (DD) N70 injectors are viable procedures for evaluating fuel effects on injector fouling. Cyclic operation appears to be superior to steady-state operation for both type injectors. Eighty-hour cyclic tests are more discriminating than 40-hour cyclic tests using the Bosch APE 113 injectors. JFTOT tests of fuels provide directional information on thermal stability-related deposits and filter plugging but show limited good correlation with IFBT DD N70 ratings, and none with IFBT Bosch APE 113 injector ratings. Deposition on injector pintles was more realistically rated by optical microscopy and Scanning Electron Microscopy (SEM) than conventional visual and bench rating methods. High-sulfur fuel readily caused sticking of Detroit Diesel injectors. Injector sticking is an important mode of injector fouling.

  3. Impact of sludge flocs on membrane fouling in membrane bioreactors

    DEFF Research Database (Denmark)

    Christensen, Morten Lykkegaard; Niessen, Wolfgang; Jørgensen, Mads Koustrup

    Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control. Large variation in filtration properties measured as flux decline was observed for the different types of sludges...... and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR. High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration...... flocs reduced membrane fouling, and more compact and strong flocs were formed if the concentration of divalent ions were high. Sludge was fractionated by centrifugation providing supernatant with soluble EPS and colloidal particles but without flocs. Filtration test on untreated sludge and supernatant...

  4. Proteins causing membrane fouling in membrane bioreactors.

    Science.gov (United States)

    Miyoshi, Taro; Nagai, Yuhei; Aizawa, Tomoyasu; Kimura, Katsuki; Watanabe, Yoshimasa

    2015-01-01

    In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.

  5. Coke fouling monitoring by electrical resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Bombardelli, Clovis; Mari, Livia Assis; Kalinowski, Hypolito Jose [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Eletrica e Informatica Industrial (CPGEI)

    2008-07-01

    An experimental method to simulate the growth of the coke fouling that occurs in the oil processing is proposed relating the thickness of the encrusted coke to its electrical resistivity. The authors suggest the use of the fouling electrical resistivity as a transducer element for determining its thickness. The sensor is basically two electrodes in an electrically isolated device where the inlay can happen in order to compose a purely resistive transducer. Such devices can be easily constructed in a simple and robust form with features capable to face the high temperatures and pressures found in relevant industrial processes. For validation, however, it is needed a relationship between the electrical resistivity and the fouling thickness, information not yet found in the literature. The present work experimentally simulates the growth of a layer of coke on an electrically insulating surface, equipped with electrodes at two extremities to measure the electrical resistivity during thermal cracking essays. The method is realized with a series of consecutive runs. The results correlate the mass of coke deposited and its electrical resistivity, and it can be used to validate the coke depositions monitoring employing the resistivity as a control parameter. (author)

  6. Impact of fouling on UV effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Dykstra, T.S. [Dalhouse Univ., Dept. of Civil Engineering, Halifax, Nova Scotia (Canada); Chauret, C. [Indiana Univ. Kokomo, Kokomo, Biological and Physical Sciences, Indiana (United States)

    2002-06-15

    In recent years ultraviolet light has gained in popularity as an attractive disinfection alternative due to its ability to inactivate bacteria and viruses. UV light has the potential to inactivate Cryptosporidium parvum and Giardia lamblia with a very low potential for the formation of harmful disinfection by-products. Previous studies have reported that particulate material present in the water can act to reduce the exposure of UV light to the receiving waters and that the interference of organic particles can serve to protect bacteria and viruses from intended disinfection. Disinfection capacity can also be reduced by organics in the source water that can accumulate on the surface of quartz sleeves. The purpose of this study was to determine the ability of a medium pressure UV light, at drinking water treatment levels, to inactivate MS 2 bacteriophage after a quartz tube has been fouled with organic rich source water for a 12- week period. To this end the inactivation of MS 2 was determined under clean and fouled conditions, in the presence and absence of humic rich water. The effect of lamp age on inactivation was also investigated. The results suggest that organic fouling of a quartz tube has a significant impact on the disinfection capacity of a medium pressure UV lamp. The presence of organics in the source water also plays a significant role in reducing the capacity of UV for bacterial and viral disinfection. Lamp age also seems to have some effect on the efficiency of UV disinfection. (author)

  7. Modification of Silicone Elastomer Surfaces with Zwitterionic Polymers: Short-Term Fouling Resistance and Triggered Biofouling Release.

    Science.gov (United States)

    Shivapooja, Phanindhar; Yu, Qian; Orihuela, Beatriz; Mays, Robin; Rittschof, Daniel; Genzer, Jan; López, Gabriel P

    2015-11-25

    We present a method for dual-mode-management of biofouling by modifying surface of silicone elastomers with zwitterionic polymeric grafts. Poly(sulfobetaine methacrylate) was grafted from poly(vinylmethylsiloxane) elastomer substrates using thiol-ene click chemistry and surface-initiated, controlled radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionality. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. Such dual-functional surfaces may be useful in developing environmentally and biologically friendly coatings for biofouling management on marine, industrial, and biomedical equipment because they can obviate the use of toxic compounds.

  8. Hydraulically irreversible fouling on ceramic MF/UF membranes: comparison of fouling indices, foulant composition and irreversible pore narrowing

    KAUST Repository

    Shang, Ran

    2015-05-06

    The application of ceramic membranes in water treatment is becoming increasing attractive because of their long life time and excellent chemical, mechanical and thermal stability. However, fouling of ceramic membranes, especially hydraulically irreversible fouling, is still a critical aspect affecting the operational cost and energy consumption in water treatment plants. In this study, four ceramic membranes with pore sizes or molecular weight cut-off (MWCO) of 0.20 μm, 0.14 μm, 300 kDa and 50 kDa were compared during natural surface water filtration with respect to hydraulically irreversible fouling index (HIFI), foulant composition and narrowing of pore size due to the irreversible fouling. Our results showed that the hydraulically irreversible fouling index (HIFI) was proportional to the membrane pore size (r2=0.89) when the same feed water was filtrated. The UF membranes showed lower HIFI values than the MF membranes. Pore narrowing (internal fouling) was found to be a main fouling pattern of the hydraulically irreversible fouling. The internal fouling was caused by monolayer adsorption of foulants with different sizes that is dependent on the size of the membrane pore.

  9. Anti-fouling properties of microstructured surfaces bio-inspired by rice leaves and butterfly wings.

    Science.gov (United States)

    Bixler, Gregory D; Theiss, Andrew; Bhushan, Bharat; Lee, Stephen C

    2014-04-01

    Material scientists often look to biology for new engineering solutions to materials science problems. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (antifouling) and lotus leaf (self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we study antifouling properties of four microstructured surfaces inspired by rice leaves and fabricated with photolithography and hot embossing techniques. Anti-biofouling effectiveness is determined with bioassays using Escherichia coli whilst inorganic fouling with simulated dirt particles. Antifouling data are presented to understand the role of surface geometrical features resistance to fouling. Conceptual modeling provides design guidance when developing novel antifouling surfaces for applications in the medical, marine, and industrial fields.

  10. Fouling Kinetics and Associated Dynamics of Structural Modifications

    DEFF Research Database (Denmark)

    Jacob, Jerome; Prádanos, Pedro; Calvo, J. I.;

    1998-01-01

    by Sartorius (ST02 and ST045, neutral) and Spectrum (SP02 and SP045, positively charged) when fouled by permeating a protein aqueous solution (bovine serum albumin (BSA) at 1 g l(-1)) under 10 kPa in a dead-end device. The structure after different fouling times is obtained by using an extended bubble point...

  11. FOULING DETECTION IN FOOD VESSELS USING INTERDIGITAL LAMB WAVE TRANSDUCER

    Institute of Scientific and Technical Information of China (English)

    JIAO Jingpin; GE Haiyan; WU Bin; HE Cunfu

    2007-01-01

    Lamb waves are used to detect fouling in food vessels. The propagation of the Lamb waves in plates exhibits many modes and dispersion characteristics, which have great influence on fouling detection. The relative distribution of the in-plane and out-of-plane displacement of the mode across the thickness of the plate will determine the sensitivity of the mode to a particular loading condition. By considering the dispersion and multi-mode characteristics of guided waves, an interdigital polyvinylidene fluoride (PVDF) transducer is designed to realize the mode selection of guided waves, and a single α0 mode is used for guided wave detection. Fouling detection experiments are conducted in the laboratory using epoxy adhesive on a thin plate. Using the interdigital PVDF transducer, three fouled areas are detected. Using one of the time-frequency analysis methods, the waveforms are further processed. This also demonstrates the validity of this method of fouling detection.

  12. Preventing colloidal fouling in reverse osmosis and nano filtration system. Application of electron beam surface analysis; Prevencion del ensuciamiento coloidal en sistemas de osmosis inversa y nanofiltracion. Aplicacion del analisis de superficies con haces de electrones.

    Energy Technology Data Exchange (ETDEWEB)

    Sanz Ataz, J.; Guerrero Gallego, L.; Taberna Camprubi, E.; Pena Garcia, N.M; Carulla Contreras, C.; Blavia Bergos, J.

    2003-07-01

    Particulate matter in natural waters and wastewaters can cause fouling in reverse osmosis and nano filtration membranes. Common foulants includes organic and inorganic colloids; hydrous aluminum and iron silicates, silt, iron and manganese oxides, calcium carbonate, microorganisms, polysaccharides, lipoproteins, biological debris, etc. Predicting fouling of dispersed materials on membrane surface and brine flow channels uses the silt density index (SDI) and modified fouling index (MFI). Scanning electron microscopy (SEM) coupled with energy X-ray microanalysis (EDX) of SDI filters contributes to obtain information about shape, size and chemical composition of foulants and cake layer. (Author) 6 refs.

  13. Organic Fouling of Graphene Oxide Membranes and Its Implications for Membrane Fouling Control in Engineered Osmosis.

    Science.gov (United States)

    Hu, Meng; Zheng, Sunxiang; Mi, Baoxia

    2016-01-19

    This study provides experimental evidence to mechanistically understand some contradicting effects of the characteristic properties of graphene oxide (GO), such as the high hydrophilicity, negative charge, strong adsorption capability, and large surface area, on the antifouling properties of GO membranes. Furthermore, this study demonstrates the effectiveness of forming a dense GO barrier layer on the back (i.e., porous) side of an asymmetric membrane for fouling control in pressure-retarded osmosis (PRO), an emerging engineered osmosis process whose advancement has been much hindered due to the severe irreversible fouling that occurs as foulants accumulate inside the porous membrane support. In the membrane fouling experiments, protein and alginate were used as model organic foulants. When operated in forward osmosis mode, the GO membrane exhibited fouling performance comparable with that of a polyamide (PA) membrane. Analysis of the membrane adsorption capacity showed that, likely due to the presence of hydrophobic regions in the GO basal plane, the GO membrane has an affinity toward organic foulants 4 to 5 times higher than the PA membrane. Such a high adsorption capacity along with a large surface area, however, did not noticeably aggravate the fouling problem. Our explanation for this phenomenon is that organic foulants are adsorbed mainly on the basal plane of GO nanosheets, and water enters the GO membrane primarily around the oxidized edges of GO, making foulant adsorption not create much hindrance to water flux. When operated in PRO mode, the GO membrane exhibited much better antifouling performance than the PA membrane. This is because unlike the PA membrane for which foulants can be easily trapped inside the porous support and hence cause severe irreversible fouling, the GO membrane allows the foulants to accumulate primarily on its surface due to the sealing effect of the GO layer assembled on the porous side of the asymmetric membrane support. Results

  14. Optimisation and Characterisation of Anti-Fouling Ternary SAM Layers for Impedance-Based Aptasensors

    Directory of Open Access Journals (Sweden)

    Anna Miodek

    2015-09-01

    Full Text Available An aptasensor with enhanced anti-fouling properties has been developed. As a case study, the aptasensor was designed with specificity for human thrombin. The sensing platform was developed on screen printed electrodes and is composed of a self-assembled monolayer made from a ternary mixture of 15-base thiolated DNA aptamers specific for human thrombin co-immobilised with 1,6-hexanedithiol (HDT and further passivated with 1-mercapto-6-hexanol (MCH. HDT binds to the surface by two of its thiol groups forming alkyl chain bridges and this architecture protects from non-specific attachment of molecules to the electrode surface. Using Electrochemical Impedance Spectroscopy (EIS, the aptasensor is able to detect human thrombin as variations in charge transfer resistance (Rct upon protein binding. After exposure to a high concentration of non-specific Bovine Serum Albumin (BSA solution, no changes in the Rct value were observed, highlighting the bio-fouling resistance of the surface generated. In this paper, we present the optimisation and characterisation of the aptasensor based on the ternary self-assembled monolayer (SAM layer. We show that anti-fouling properties depend on the type of gold surface used for biosensor construction, which was also confirmed by contact angle measurements. We further studied the ratio between aptamers and HDT, which can determine the specificity and selectivity of the sensing layer. We also report the influence of buffer pH and temperature used for incubation of electrodes with proteins on detection and anti-fouling properties. Finally, the stability of the aptasensor was studied by storage of modified electrodes for up to 28 days in different buffers and atmospheric conditions. Aptasensors based on ternary SAM layers are highly promising for clinical applications for detection of a range of proteins in real biological samples.

  15. Optimisation and Characterisation of Anti-Fouling Ternary SAM Layers for Impedance-Based Aptasensors.

    Science.gov (United States)

    Miodek, Anna; Regan, Edward M; Bhalla, Nikhil; Hopkins, Neal A E; Goodchild, Sarah A; Estrela, Pedro

    2015-09-29

    An aptasensor with enhanced anti-fouling properties has been developed. As a case study, the aptasensor was designed with specificity for human thrombin. The sensing platform was developed on screen printed electrodes and is composed of a self-assembled monolayer made from a ternary mixture of 15-base thiolated DNA aptamers specific for human thrombin co-immobilised with 1,6-hexanedithiol (HDT) and further passivated with 1-mercapto-6-hexanol (MCH). HDT binds to the surface by two of its thiol groups forming alkyl chain bridges and this architecture protects from non-specific attachment of molecules to the electrode surface. Using Electrochemical Impedance Spectroscopy (EIS), the aptasensor is able to detect human thrombin as variations in charge transfer resistance (Rct) upon protein binding. After exposure to a high concentration of non-specific Bovine Serum Albumin (BSA) solution, no changes in the Rct value were observed, highlighting the bio-fouling resistance of the surface generated. In this paper, we present the optimisation and characterisation of the aptasensor based on the ternary self-assembled monolayer (SAM) layer. We show that anti-fouling properties depend on the type of gold surface used for biosensor construction, which was also confirmed by contact angle measurements. We further studied the ratio between aptamers and HDT, which can determine the specificity and selectivity of the sensing layer. We also report the influence of buffer pH and temperature used for incubation of electrodes with proteins on detection and anti-fouling properties. Finally, the stability of the aptasensor was studied by storage of modified electrodes for up to 28 days in different buffers and atmospheric conditions. Aptasensors based on ternary SAM layers are highly promising for clinical applications for detection of a range of proteins in real biological samples.

  16. Heat mass transfer model of fouling process of calcium carbonate on heat transfer surface

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new heat mass transfer model was developed to predict the fouling process of calcium carbonate on heat transfer surface. The model took into account not only the crystallization fouling but also the particle fouling which was formed on the heat transfer surface by the suspension particles of calcium carbonate in the su- persaturated solution. Based on experimental results of the fouling process, the deposition and removal rates of the mixing fouling were expressed. Furthermore, the coupling effect of temperature with the fouling process was considered in the physics model. As a result the fouling resistance varying with time was obtained to describe the fouling process and the prediction was compared with experimental data under same conditions. The results showed that the present model could give a good prediction of fouling process, and the deviation was less than 15% of the experimental data in most cases. The new model is credible to predict the fouling process.

  17. Membrane fouling in a membrane bioreactor (MBR): sludge cake formation and fouling characteristics.

    Science.gov (United States)

    Ping Chu, Hiu; Li, Xiao-Yan

    2005-05-05

    A submerged membrane bioreactor (MBR) with a working volume of 1.4 L and a hollow fiber microfiltration membrane was used to treat a contaminated raw water supply at a short hydraulic retention time (HRT) of approximately 1 h. Filtration flux tests were conducted regularly on the membrane to determine various fouling resistances, and confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were employed to characterize the biofouling development and sludge cake formation on the membrane. The experimental results demonstrate that the MBR is highly effective in drinking water treatment for the removal of organic pollutants, ammonia, and UV absorbance. During the MBR operation, the fouling materials were not uniformly distributed on the entire surface of all of the membrane fibers. The membrane was covered partially by a static sludge cake that could not be removed by the shear force of aeration, and partially by a thin sludge film that was frequently washed away by aeration turbulence. The filtration resistance coefficients were 308.4 x 10(11) m(-1) on average for the sludge cake, 32.5 x 10(11) m(-1) on average for the dynamic sludge film, and increased from 10.5 x 10(11) to 59.7 x 10(11) m(-1) for the membrane pore fouling after 10 weeks of MBR operation at a filtration flux of 0.5 m3/m2 x d. Polysaccharides and other biopolymers were found to accumulate on the membrane, and hence decreased membrane permeability. More important, the adsorption of biopolymers on the membrane modified its surface property and led to easier biomass attachment and tighter sludge cake deposition, which resulted in a progressive sludge cake growth and serious membrane fouling. The sludge cake coverage on the membrane can be minimized by the separation, with adequate space, of the membrane filters, to which sufficient aeration turbulence can then be applied.

  18. A New Concept of Ultrafiltration Fouling Control: Backwashing with Low Ionic Strength Water

    OpenAIRE

    Li, S.

    2011-01-01

    Ultrafiltration (UF) is a proven technology in water treatment nowadays. However, fouling remains a major challenge in the operation of UF, especially in regard to colloidal NOM fouling. In general, a number of colloidal NOM fouling mechanisms may occur, such as adsorption, gel formation. Colloidal NOM fouling is influenced by multivalent cations, ionic strength and pH. In order to control membrane fouling, different pretreatments such as powder activated carbon adsorption, lime softening, io...

  19. CONCENTRIC TUBE-FOULING RIG FOR INVESTIGATION OF FOULING DEPOSIT FORMATION FROM PASTEURISER OF VISCOUS FOOD LIQUID

    Directory of Open Access Journals (Sweden)

    N. I. KHALID

    2013-02-01

    Full Text Available This paper reports the work on developing concentric tube-fouling rig, a new fouling deposit monitoring device. This device can detect and quantify the level of fouling deposit formation. It can also functioning as sampler for fouling deposit study, which can be attached at any food processing equipment. The design is initiated with conceptual design. The rig is designed with inner diameter of 7 cm and with tube length of 37 cm. A spiral insert with 34.5 cm length and with 5.4 cm diameter is fitted inside the tube to ensure the fluid flows around the tube. In this work, the rig is attached to the lab-scale concentric tube-pasteurizer to test its effectiveness and to collect a fouling sample after pasteurization of pink guava puree. Temperature changes are recorded during the pasteurization and the data is used to plot the heat transfer profile. Thickness of the fouling deposit is also measured. The trends for thickness, heat resistance profile and heat transfer profile for concentric tube-fouling rig matched the trends obtained from lab-scale concentric tube-pasteurizer very well. The findings from this work have shown a good potential of this rig however there is a limitation with spiral insert, which is discussed in this paper.

  20. Biologic

    CERN Document Server

    Kauffman, L H

    2002-01-01

    In this paper we explore the boundary between biology and the study of formal systems (logic). In the end, we arrive at a summary formalism, a chapter in "boundary mathematics" where there are not only containers but also extainers ><, entities open to interaction and distinguishing the space that they are not. The boundary algebra of containers and extainers is to biologic what boolean algebra is to classical logic. We show how this formalism encompasses significant parts of the logic of DNA replication, the Dirac formalism for quantum mechanics, formalisms for protein folding and the basic structure of the Temperley Lieb algebra at the foundations of topological invariants of knots and links.

  1. Fouling-resistant polymer brush coatings

    KAUST Repository

    Thérien-Aubin, Héloïse

    2011-11-01

    A major problem to be addressed with thin composite films used in processes such as coatings or water purification is the biofouling of the surface. To address this problem in a model system, functionalized polyaramide membranes containing an atom transfer radical polymerization (ATRP) initiator were synthesized as a versatile approach to easily modify the surface properties of the polyaramide. Poly(methacrylic acid) brushes were grown using surface initiated ATRP followed by the functionalization of the poly(methacrylic acid) brushes with different side-chains chosen to reduce adhesion between the membrane and foulant. The relation between membrane fouling and the physicochemical properties of the surface was investigated in detail. © 2011 Elsevier Ltd. All rights reserved.

  2. Retention of Silica Nanoparticles in a Lab-Scale Membrane Bioreactor: Implications for Process Performance and Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Mark Larracas Sibag

    2016-07-01

    Full Text Available In conventional activated sludge (CAS involving aerobic biological processes, the retention of silica nanoparticles (SiO2 NPs has no detrimental effect on chemical oxygen demand (COD and ammonia nitrogen (NH3–N removal. However, for the membrane bioreactor (MBR system, which is also based on the activated sludge process in addition to the membrane separation process, it has implications not only on the process performance but also on membrane fouling. To investigate these two implications in lab-scale experiments, we continuously operated a control MBR and two experimental MBRs, in which the 28 nm SiO2 NPs and 144 nm SiO2 NPs were added separately to the influent at a final concentration of 100 mg/L. Although the retention of SiO2 NPs in the MBR, as confirmed by dynamic light scattering (DLS analysis, did not compromise the COD and NH3–N removal, it resulted in substantial increases in the transmembrane pressure (TMP suggesting the onset of membrane fouling. Analyses by batch-dead end filtration revealed the same fouling trend as observed during the continuous MBR experiments; membrane fouling is aggravated in the presence of SiO2 NPs. This was evident from permeate flux decline of between 30% and 74% at very low TMP (5 kPa and the further increases in the total resistance.

  3. Fouling Characteristics and Prevention Techniques for Membrane Bioreactor

    Institute of Scientific and Technical Information of China (English)

    LU Hua; WANG Zhi-qiang; YANG Jin-ying

    2005-01-01

    Membrane fouling is the main problem of membrane bioreactors (MBR), which seriously influences its wastewater treatment effect and running. The characteristics of microbiology and hydrodynamics concerning membrane fouling were investigated and the measure was put forward for optimum operation of MBR. The measure is that 1) the parameters of activated sludge concentration (X) and membrane flux should be lower than the critical values of X and membrane flux respectively, and 2) the activated sludge should be discharged periodically. The experimental results show that the combination backwashing of gas and permeated effluent is better than single gas backwashing or single permeated effluent backwashing. This technique can remove the cake layer deposited on the membrane surface, decrease the membrane fouling, and recover the membrane flux effectively. So it is effective for prevention of membrane fouling.

  4. Scaling and particulate fouling in membrane filtration systems

    NARCIS (Netherlands)

    Boerlage, S.F.E.

    2001-01-01

    Membrane filtration technologies have emerged as cost competitive and viable techniques in drinking and industrial water production. Despite advancements in membrane manufacturing and technology, membrane scaling and fouling remain major problems and may limit future growth in the industry. Scaling

  5. Membrane fouling control by ultrasound in an anaerobic membrane bioreactor

    Institute of Scientific and Technical Information of China (English)

    SUI Pengzhe; WEN Xianghua; HUANG Xia

    2007-01-01

    In this study,ultrasound was used to control the membrane fouling online in an anaerobic membrane bioreactor (AMBR).Short-term running experiments were carried out under different operating conditions to explore feasible ultrasonic parameters.The experimental results indicated that when the crossflow velocity was more than 1.0 m/s,membrane fouling could be controlled effectively only by hydrodynamic methods without ultrasound.When ultrasound was applied,an ultrasonic power range of 60-150 W was suitable for the membrane fouling control in the experimental system.The experimental results showed that the membrane fouling was controlled so well that membrane filtration resistance(ΣR) could stay at 5×1011 m-1 for more than a week with the crossflow velocity of 0.75 m/s,which equaled the effect of crossflow velocity of more than 1.0 m/s without ultrasound.

  6. Transparent and Explicable Boiler Fouling Monitoring with Fuzzy Neural Newtwork

    Institute of Scientific and Technical Information of China (English)

    BinWu; You-TingShen

    1998-01-01

    Fouling on boiler beating surfaces is one of the important factors that damage boiler's economical performance and safety,with on-line monitoring of foiling states on boler heating surfaces,it is possible to optimize sootblower system,to visualize fouling states,to improve performance,as well as to remedy the insufficiency of experiment research in boiler heating surface fouling process.New method based on Fuzzy Neural Network(FNN) is presented to monitor fouling states on boiler heating surfaces on-line.Compared with regular methods,since FNN's reasoning process is transparent and comprehensible,it is possible to explain and comprehend reasoning process,which makes the FNN based system perform as an additional operation consulting system.

  7. Fouling in small hydro projects; Verschmutzung von Kleinwasserkraftwerken - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Abgottspon, A.; Staubli, T.

    2010-03-15

    This comprehensive final report for the Swiss Federal Office of Energy (SFOE) takes a look at fouling problems encountered in small hydro installations. The report is based on ten interviews made with operators of small hydro power stations in Switzerland. A parallel project carried out in Germany is mentioned. A large variation in the degree of fouling in the various hydro power stations is noted. Sources such as leaves in autumn and algae are discussed, as are the various rinsing procedures used to clear the turbines of fouling. Power losses are discussed and measures that can be taken to prevent fouling are described. Measurements made at an installation in Freienstein, Switzerland, are presented and discussed. The report is completed with an appendix containing calculations, details on the Freienstein power plant and the results of interviews made with the ten hydro power installations examined.

  8. Records of Australian Fouling Organisms: Sessile Barnacles (Crustacea, Cirripedia),

    Science.gov (United States)

    1981-04-01

    Dr. W.A. Newman) Laboratorio de Ensayo de Materiales e Investigaciones Tecnologicas (LEMIT), Argentina. (Attention: Dr. V. Rascio) Dept. of Zoology...AD-A105 265 MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA) FIG B/1 RECORDS OF AUSTRALIAN FOULING ORGANISMS: SESSILE BARNACLES (CRU--ETC(U) APR 81 J A...SCIENCE AND TECHNOLOGY ORGANISATION MATERIALS RESEARCH LABORATORIES MELBOURNE, VICTORIA REPORT . MRL-R-809 RECORDS OF AUSTRALIAN FOULING ORGANISMS: SESSILE

  9. Ultrafiltration Membrane Fouling and the Effect of Ion Exchange Resins

    KAUST Repository

    Jamaly, Sanaa

    2011-12-01

    Membrane fouling is a challenging process for the ultrafiltration membrane during wastewater treatment. This research paper determines the organic character of foulants of different kinds of wastewater before and after adding some ion exchange resins. Two advanced organic characterization methods are compared in terms of concentration of dissolved organic carbons: The liquid chromatography with organic carbon (LC-OCD) and Shimadzu total organic carbon (TOC). In this study, two secondary wastewater effluents were treated using ultrafiltration membrane. To reduce fouling, pretreatment using some adsorbents were used in the study. Six ion exchange resins out of twenty were chosen to compare the effect of adsorbents on fouling membrane. Based on the percent of dissolved organic carbon’s removal, three adsorbents were determined to be the most efficient (DOWEX Marathon 11 anion exchange resin, DOWEX Optipore SD2 polymeric adsorbent, and DOWEX PSR2 anion exchange), and three other ones were determined to the least efficient (DOWEX Marathon A2 anion exchange resin, DOWEX SAR anion exchange resin, and DOWEX Optipore L493 polymeric adsorbent). Organic characterization for feed, permeate, and backwash samples were tested using LC-OCD and TOC to better understand the characteristics of foulants to prevent ultrafiltration membrane fouling. The results suggested that the polymeric ion exchange resin, DOWEX SD2, reduced fouling potential for both treated wastewaters. All the six ion exchange resins removed more humic fraction than other organic fractions in different percent, so this fraction is not the main for cause for UF membrane fouling. The fouling of colloids was tested before and after adding calcium. There is a severe fouling after adding Ca2+ to effluent colloids.

  10. Slagging and Fouling Characteristics of HRSG for Ferrosilicon Electric Furnaces

    OpenAIRE

    2015-01-01

    The slagging and fouling characteristics of the heat recovery steam generator (HRSG) for ferrosilicon electric furnaces are discussed in this paper. Three ash samples were taken from the HRSG of a ferrosilicon furnace in Ningxia Province, China, which suffered from serious slagging and fouling. X-ray fluorescence (XRF), X-ray powder diffraction (XRD) and scanning electron microscope (SEM) were used to analyze the ash samples. The results show that low melting point salt Na 2 SO 4 and composit...

  11. High Flux, Fouling Resistant Membranes for RO Pretreatment

    Science.gov (United States)

    2012-05-31

    improved flux and fouling resistance . This in turn will lead to more compact and efficient filtration systems that reduce maintenance and downtime...size, and resistance to protein fouling by BSA filtration . Hollow Fiber Development and Testing Hollow fibers were produced by a generally...layer during dead- end filtration . The shear forces in cross-flow operation can impact the effective particle size in the feed and compact the cake

  12. Kinetic study of seawater reverse osmosis membrane fouling

    KAUST Repository

    Khan, Muhammad

    2013-10-01

    Reverse osmosis (RO) membrane fouling is not a static state but a dynamic phenomenon. The investigation of fouling kinetics and dynamics of change in the composition of the foulant mass is essential to elucidate the mechanism of fouling and foulant-foulant interactions. The aim of this work was to study at a lab scale the fouling process with an emphasis on the changes in the relative composition of foulant material as a function of operating time. Fouled membrane samples were collected at 8 h, and 1, 2, and 4 weeks on a lab-scale RO unit operated in recirculation mode. Foulant characterization was performed by CLSM, AFM, ATR-FTIR, pyrolysis GC-MS, and ICP-MS techniques. Moreover, measurement of active biomass and analysis of microbial diversity were performed by ATP analysis and DNA extraction, followed by pyro-sequencing, respectively. A progressive increase in the abundance of almost all the foulant species was observed, but their relative proportion changed over the age of the fouling layer. Microbial population in all the membrane samples was dominated by specific groups/species belonging to Proteobacteria and Actinobacteria phyla; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age. © 2013 American Chemical Society.

  13. Ammonia recovery from agricultural wastes by membrane distillation: fouling characterization and mechanism.

    Science.gov (United States)

    Zarebska, A; Nieto, D Romero; Christensen, K V; Norddahl, B

    2014-06-01

    One of the main obstacles impeding implementation of membrane distillation for the recovery and concentration of ammonia from swine manure is wetting caused by fouling. Due to the different types of fouling which can occur in a membrane system, foulants characterization is a complex problem. To elucidate the fouling mechanism, deposit morphology and composition of foulants have been determined using Scanning Electron Microscopy, X-ray Energy Dispersive Spectrometry, Attenuated Total Reflectance Infrared Spectrometry, Ion chromatography and Inductively coupled plasma-optical emission spectroscopy. Based on the analysis of fouled membranes, it is concluded that membrane fouling is dominated by organic fouling in combination with deposits of inorganic elements and microorganisms. After a week of running the membrane process without cleaning, the average fouling layer thickness was estimated to 10-15 μm. The fouling layer further results in a loss of membrane hydrophobicity. This indicates that fouling could be a severe problem for membrane distillation performance.

  14. High-resolution phylogenetic analysis of residual bacterial species of fouled membranes after NaOCl cleaning.

    Science.gov (United States)

    Navarro, Ronald R; Hori, Tomoyuki; Inaba, Tomohiro; Matsuo, Kazuyuki; Habe, Hiroshi; Ogata, Atsushi

    2016-05-01

    Biofouling is one of the major problems during wastewater treatment using membrane bioreactors (MBRs). In this regard, sodium hypochlorite (NaOCl) has been widely used to wash fouled membranes for maintenance and recovery purposes. Advanced chemical and biological characterization was conducted in this work to evaluate the performance of aqueous NaOCl solutions during washing of polyacrylonitrile membranes. Fouled membranes from MBR operations supplemented with artificial wastewater were washed with 0.1% and 0.5% aqueous NaOCl solutions for 5, 10 and 30 min. The changes in organics composition on the membrane surface were directly monitored by an attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectrometer. In addition, high-throughput Illumina sequencing of 16S rRNA genes was applied to detect any residual microorganisms. Results from ATR-FT-IR analysis indicated the complete disappearance of functional groups representing different fouling compounds after at least 30 min of treatment with 0.1% NaOCl. However, the biomolecular survey revealed the presence of residual bacteria even after 30 min of treatment with 0.5% NaOCl solution. Evaluation of microbial diversity of treated samples using Chao1, Shannon and Simpson reciprocal indices showed an increase in evenness while no significant decline in richness was observed. These implied that only the population of dominant species was mainly affected. The high-resolution phylogenetic analysis revealed the presence of numerous operational taxonomic units (OTUs) whose close relatives exhibit halotolerance. Some OTUs related to thermophilic and acid-resistant strains were also identified. Finally, the taxonomic analysis of recycled membranes that were previously washed with NaOCl also showed the presence of numerous halotolerant-related OTUs in the early stage of fouling. This further suggested the possible contribution of such chemical tolerance on their survival against NaOCl washing, which in turn

  15. A review on the use of membrane technology and fouling control for olive mill wastewater treatment.

    Science.gov (United States)

    Pulido, Javier Miguel Ochando

    2016-09-01

    Olive mill effluents (OME) by-produced have significantly increased in the last decades as a result of the boost of the olive oil agro-industrial sector and due to the conversion into continuous operation centrifugation technologies. In these effluents, the presence of phytotoxic recalcitrant pollutants makes them resistant to biological degradation and thus inhibits the efficiency of biological and conventional processes. Many reclamation treatments as well as integrated processes for OME have already been proposed and developed but not led to completely satisfactory and cost-effective results. Olive oil industries in its current status, typically small mills dispersed, cannot afford such high treatment costs. Furthermore, conventional treatments are not able to abate the significant dissolved monovalent and divalent ions concentration present in OME. Within this framework, membrane technology offers high efficiency and moderate investment and maintenance expenses. Wastewater treatment by membrane technologies is growing in the recent years. This trend is owed to the fact of the availability of new membrane materials, membrane designs, membrane module concepts and general know-how, which have promoted credibility among investors. However, fouling reduces the membrane performances in time and leads to premature substitution of the membrane modules, and this is a problem of cost efficiency since wastewater treatment must imply low operating costs. Appropriate fouling inhibition methods should assure this result, thus making membrane processes for wastewater stream treatment both technically and economically feasible. In this paper, the treatment of the effluents by-produced in olive mills, generally called olive mill wastewaters, will be addressed. Within this context, the state of the art of the different pretreatments and integral membrane processes proposed up to today will be gathered and discussed, with an insight in the problem of fouling.

  16. KARAKTERISTIK INTERAKSI MEMBRAN-FOULANT DAN FOULANT-FOULANT SEBAGAI DASAR PENGENDALIAN FOULING

    Directory of Open Access Journals (Sweden)

    Heru Susanto

    2012-05-01

    Full Text Available THE CHARACTERISTICS OF MEMBRANE-FOULANT AND FOULANT-FOULANT INTERACTIONS AS THE BASIS FOR CONTROL OF FOULING. Industrial membrane applications for solid liquid and liquid-liquid filtration are limited by fouling and concentration polarization. Because fouling significantly reduces the membrane performance and often changes the membrane selectivity, efforts to overcome the fouling problem are very important from practical applications point of view. This paper presents the basic knowledge required to control fouling and recent development in fouling control including the method developed by the author. Control of fouling can be done by (i commercial membrane modification (post modification by photo-graft polymerization, (ii modification by polymer blending during membrane manufacturing and (iii integration of a pretreatment into membrane processes. The results showed that all the developed methods can significantly reduce the resulting fouling; however, none of the method could totally remove the occurring fouling. The understanding of the membrane-foulant and foulant-foulant interactions is the key to success in control of fouling.Aplikasi teknologi membran untuk pemisahan padat cair di  berbagai industri dibatasi oleh peristiwa fouling yang menyebabkan penurunan laju produk dan perubahan selektifitas membran. Oleh karena itu, pengendalian fouling merupakan upaya yang mutlak harus dilakukan. Makalah ini mempresentasikan pengetahuan dasar yang diperlukan untuk pengendalian fouling dan perkembangan terkini dalam pengendalian fouling termasuk hasil-hasil yang telah dikembangkan oleh penulis. Pengendalian fouling dilakukan dengan (i modifikasi membran komersial (post modification menggunakan metode photo-grafting, (ii modifikasi dengan pencampuran polimer selama proses pembuatan (polymer blend dan (iii integrasi unit perlakuan awal (pre-treatment dengan proses membran. Hasil penelitian menunjukkan bahwa kesemua metode yang dikembangkan dapat

  17. Superhydrophilic thin-film composite forward osmosis membranes for organic fouling control: fouling behavior and antifouling mechanisms.

    Science.gov (United States)

    Tiraferri, Alberto; Kang, Yan; Giannelis, Emmanuel P; Elimelech, Menachem

    2012-10-16

    This study investigates the fouling behavior and fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of fouling, the intermolecular interactions between the foulants and the membrane surface are analyzed by direct force measurement using atomic force microscopy. Lower adhesion forces are observed for the superhydrophilic membranes compared to the control thin-film composite polyamide membranes. The magnitude and distribution of adhesion forces for the different membrane surfaces suggest that the antifouling properties of the superhydrophilic membranes originate from the barrier provided by the tightly bound hydration layer at their surface, as well as from the neutralization of the native carboxyl groups of thin-film composite polyamide membranes.

  18. Fouling of a spiral-wound reverse osmosis membrane processing swine wastewater: effect of cleaning procedure on fouling resistance.

    Science.gov (United States)

    Camilleri-Rumbau, M S; Masse, L; Dubreuil, J; Mondor, M; Christensen, K V; Norddahl, B

    2016-01-01

    Swine manure is a valuable source of nitrogen, phosphorus and potassium. After solid-liquid separation, the resulting swine wastewater can be concentrated by reverse osmosis (RO) to produce a nitrogen-potassium rich fertilizer. However, swine wastewater has a high fouling potential and an efficient cleaning strategy is required. In this study, a semi-commercial farm scale RO spiral-wound membrane unit was fouled while processing larger volumes of swine wastewater during realistic cyclic operations over a 9-week period. Membrane cleaning was performed daily. Three different cleaning solutions, containing SDS, SDS+EDTA and NaOH were compared. About 99% of the fouling resistance could be removed by rinsing the membrane with water. Flux recoveries (FRs) above 98% were achieved for all the three cleaning solutions after cleaning. No significant differences in FR were found between the cleaning solutions. The NaOH solution thus is a good economical option for cleaning RO spiral-wound membranes fouled with swine wastewater. Soaking the membrane for 3 days in permeate water at the end of each week further improved the FR. Furthermore, a fouling resistance model for predicting the fouling rate, permeate flux decay and cleaning cycle periods based on processing time and swine wastewater conductivity was developed.

  19. Superhydrophilic Thin-Film Composite Forward Osmosis Membranes for Organic Fouling Control: Fouling Behavior and Antifouling Mechanisms

    KAUST Repository

    Tiraferri, Alberto

    2012-10-16

    This study investigates the fouling behavior and fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of fouling, the intermolecular interactions between the foulants and the membrane surface are analyzed by direct force measurement using atomic force microscopy. Lower adhesion forces are observed for the superhydrophilic membranes compared to the control thin-film composite polyamide membranes. The magnitude and distribution of adhesion forces for the different membrane surfaces suggest that the antifouling properties of the superhydrophilic membranes originate from the barrier provided by the tightly bound hydration layer at their surface, as well as from the neutralization of the native carboxyl groups of thin-film composite polyamide membranes. © 2012 American Chemical Society.

  20. Impact of organic fractions identified by SEC and fluorescence EEM on the hydraulic reversibility of ultrafiltration membrane fouling by secondary effluents

    KAUST Repository

    Haberkampa, Jens

    2011-05-01

    Loss of membrane filtration performance due to organic fouling is still a significant drawback for the application of low-pressure membranes in tertiary wastewater treatment. The present study investigates the relevance of different organic fractions present in secondary effluents in terms of hydraulically reversible and irreversible fouling of hollow-fibre ultrafiltration membranes. A good correlation between the hydraulically reversible filtration resistance and the total organic biopolymer concentration according to size exclusion chromatography (SEC) was observed. Qualitatively biopolymers consist mainly of polysaccharides as well as proteins with high molecular weight. Polysaccharides are retained by the membrane pores, but can be removed by simple UF backwashing. On the other hand, fluorescence excitation-emission matrix (EEM) analysis indicates that the extent of the hydraulically irreversible fouling correlates with the presence of protein-like substances. Removal of protein-like substances by biological slow sand filtration or chemical coagulation results in the significant reduction of the hydraulically irreversible fouling, which is presumably due to proteins in the molecular range of biopolymers. In contrast to the comparatively low sensitivity of colorimetric methods for the analysis of proteins and polysaccharides, the combined application of size exclusion chromatography and fluorescence EEM analysis is a promising tool for the determination of the organic fouling propensity of secondary effluents. ©2011 Desalination Publications. All rights reserved.

  1. Effect of activated sludge properties and membrane operation conditions on fouling characteristics in membrane bioreactors.

    Science.gov (United States)

    Choi, Hyeok; Zhang, Kai; Dionysiou, Dionysios D; Oerther, Daniel B; Sorial, George A

    2006-06-01

    Biofouling control is considered to be a major challenge in operating membrane bioreactors (MBRs) for the treatment of wastewater. This study examined the impact of biological, chemical, and physical properties of activated sludge on membrane filtration performance in laboratory-scale MBRs. Sludges with different microbial communities were produced using pseudo-continuous stirred-tank reactors and pseudo-plug flow reactors treating a synthetic paper mill wastewater. Various filtration resistances were used to investigate membrane fouling characteristics, and molecular biology tools targeting 16S ribosomal DNA gene sequences were used to identify predominant bacterial populations in the sludges or attached to the fouled membranes. Filtration experiments using axenic cultures of Escherichia coli, Acinetobacter calcoaceticus, and Gordonia amarae were also performed to better understand the initiation and development of biofouling. The results showed that the tendency of membranes to biofoul depended upon membrane operating conditions as well as the properties of the activated sludge in the MBR systems. Specific bacterial populations, which were not dominant in the activated sludges, were selectively accumulated on the membrane surface leading to the development of irreversible biofouling.

  2. Recovery of real dye bath wastewater using integrated membrane process: considering water recovery, membrane fouling and reuse potential of membranes.

    Science.gov (United States)

    Balcik-Canbolat, Cigdem; Sengezer, Cisel; Sakar, Hacer; Karagunduz, Ahmet; Keskinler, Bulent

    2016-12-30

    It has been recognized by the whole world that textile industry which produce large amounts of wastewater with strong color and toxic organic compounds is a major problematical industry requiring effective treatment solutions. In this study, reverse osmosis (RO) membranes were tested on biologically treated real dye bath wastewater with and without pretreatment by nanofiltration (NF) membrane to recovery. Also membrane fouling and reuse potential of membranes were investigated by multiple filtrations. Obtained results showed that only NF is not suitable to produce enough quality to reuse the wastewater in a textile industry as process water while RO provide successfully enough permeate quality. The results recommend that integrated NF/RO membrane process is able to reduce membrane fouling and allow long-term operation for real dye bath wastewater.

  3. Long-term effect on membrane fouling in a new membrane bioreactor as a pretreatment to seawater desalination.

    Science.gov (United States)

    Jeong, Sanghyun; Rice, Scott A; Vigneswaran, Saravanamuthu

    2014-08-01

    Submerged membrane adsorption bio-reactors (SMABR) were investigated as a new pretreatment for seawater reverse osmosis (SWRO) desalination. They were tested with different doses of powder activated carbon (PAC) on-site for a long-term. The biofouling on the membrane was assessed in terms of DNA (cells) and polysaccharide distribution. MBR without PAC addition resulted in severe fouling on membrane. When PAC is added in the MBR, PAC could reduce the organic fouling. Hence the biofilm formation on membrane was reduced without any membrane damage. PAC also helped to remove low molecular weight (LMW) organics responsible for biofouling of RO membrane. A linear correlation between assimilable organic carbon (AOC) and LMW organics was observed. A small amount of PAC (2.4-8.0g of PAC/m(3) of seawater) was sufficient to reduce biofouling. It indicated that SMABR is an environmentally-friendly biological pretreatment to reduce biofouling for SWRO.

  4. Rejection of Organic Micropollutants by Clean and Fouled Nanofiltration Membranes

    Directory of Open Access Journals (Sweden)

    Lifang Zhu

    2015-01-01

    Full Text Available The rejection of organic micropollutants, including three polycyclic aromatic hydrocarbons (PAHs and three phthalic acid esters (PAEs, by clean and fouled nanofiltration membranes was investigated in the present study. The rejection of organic micropollutants by clean NF90 membranes varied from 87.9 to more than 99.9%, while that of NF270 membranes ranged from 32.1 to 92.3%. Clear time-dependence was observed for the rejection of hydrophobic micropollutants, which was attributed to the adsorption of micropollutants on the membrane. Fouling with humic acid had a negligible influence on the rejection of organic micropollutants by NF90 membranes, while considerable effects were observed with NF270 membranes, which are significantly looser than NF90 membranes. The observed enhancement in the rejection of organic micropollutants by fouled NF270 membranes was attributed to pore blocking, which was a dominating fouling mechanism for loose NF membranes. Changes in the ionic strength (from 10 to 20 mM reduced micropollutant rejection by both fouled NF membranes, especially for the rejection of dimethyl phthalate and diethyl phthalate by NF270 membranes (from 65.8 to 25.0% for dimethyl phthalate and 75.6 to 33.3% for diethyl phthalate.

  5. In-line quantification and characterization of membrane fouling

    KAUST Repository

    Bucs, Szilard

    2016-06-16

    Methods of detecting, quantifying and/or characterizing the fouling of a device from a combination of pressure and spectroscopic data are provided. The device can be any device containing components susceptible to fouling. Components can include membranes, pipes, or reactors. Suitable devices include membrane devices, heat exchangers, and chemical or bio-reactors. Membrane devices can include, for example, microfiltration devices, ultrafiltration devices, nanofiltration devices, reverse osmosis, forward osmosis, osmosis, reverse electrodialysis, electro- deionisation or membrane distillation devices. The methods can be applied to any type of membrane, including tubular, spiral, hollow fiber, flat sheet, and capillary membranes. The spectroscopic characterization can include measuring one or more of the absorption, fluorescence, or raman spectroscopic data of one or more foulants. The methods can allow for the early detection and/or characterization of fouling. The characterization can include determining the specific foulant(s) or type of foulant(s) present. The characterization of fouling can allow for the selection of an appropriate de-fouling method and timing.

  6. The new performance calculation method of fouled axial flow compressor.

    Science.gov (United States)

    Yang, Huadong; Xu, Hong

    2014-01-01

    Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds' law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail.

  7. The New Performance Calculation Method of Fouled Axial Flow Compressor

    Directory of Open Access Journals (Sweden)

    Huadong Yang

    2014-01-01

    Full Text Available Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds’ law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail.

  8. Regeneration of sulfur-fouled bimetallic Pd-based catalysts.

    Science.gov (United States)

    Chaplin, Brian P; Shapley, John R; Werth, Charles J

    2007-08-01

    Pd-based catalysts provide efficient and selective reduction of several drinking water contaminants, but their long-term application requires effective treatments for catalyst regeneration following fouling by constituents in natural waters. This studytested alumina-supported Pd-Cu and Pd-In bimetallic catalysts for nitrate reduction with H2 after sulfide fouling and oxidative regeneration procedures. Both catalysts were severely deactivated after treatment with microM levels of sulfide. Regeneration was attempted with dissolved oxygen, hydrogen peroxide, sodium hypochlorite, and heated air. Only sodium hypochlorite and heated air were effective regenerants, specifically restoring nitrate reduction rates for a Pd-In/gamma-Al2O3 catalyst from 20% to between 39 and 60% of original levels. Results from ICP-MS revealed that sodium hypochlorite caused dissolution of Cu from the Pd-Cu catalyst but that the Pd-In catalyst was chemically stable over a range of sulfide fouling and oxidative regenerative conditions. Analysis byXPS indicated that PdS and In2S3 complexes form during sulfide fouling, where sulfur is present as S2-, and that regeneration with sodium hypochlorite converts a portion of the S2- to S6+, with a corresponding increase in reduction rates. These results indicate that Pd-In catalysts show exceptional promise for being robust under fouling and regeneration conditions that may occur when treating natural waters.

  9. Zeta-potential of fouled thin film composite membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, K.; Hachisuka, H.; Nakamura, T. [Nitto denko Corp., Ibaraki, (Japan); Kimura, S. [Kogakuin University, Tokyo (Japan). Dept. of Environ. Chemical Engineering; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering

    1999-10-01

    The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It was confirmed that this method could be effectively applied to analyze the fouling of such membranes. It is known that the water flux of membranes drastically decreases as a result of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SEM, EDX and FT-IR, their presence could be clarified by the profile measurements of the surface zeta-potential. The profiles of the membrane surface zeta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring method of surface zeta-potentials allowed us to analyze a very small amount of fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film composite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that this method is easy and effective for the reverse osmosis membrane surface analysis of adsorbed materials such as surfactants. (author)

  10. Species interactions within a fouling diatom community: Roles of nutrients, initial inoculum and competitive strategies

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Anil, A

    Diatoms constitute an important component of the fouling community. Although a lot of work has dealt with the fouling diatom community structure, work on the species interactions within the community is still meager. In this regard, a study...

  11. Industrial fouling: problem characterization, economic assessment, and review of prevention, mitigation, and accommodation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Garrett-Price, B.A.; Smith, S.A.; Watts, R.L.

    1984-02-01

    A comprehensive overview of heat exchanger fouling in the manufacturing industries is provided. Specifically, this overview addresses: the characteristics of industrial fouling problems; the mitigation and accommodation techniques currently used by industry; and the types and magnitude of costs associated with industrial fouling. A detailed review of the fouling problems, costs and mitigation techniques is provided for the food, textile, pulp and paper, chemical, petroleum, cement, glass and primary metals industries.

  12. Pretreatment and Membrane Hydrophilic Modification to Reduce Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Huaqiang Chu

    2013-09-01

    Full Text Available The application of low pressure membranes (microfiltration/ultrafiltration has undergone accelerated development for drinking water production. However, the major obstacle encountered in its popularization is membrane fouling caused by natural organic matter (NOM. This paper firstly summarizes the two factors causing the organic membrane fouling, including molecular weight (MW and hydrophilicity/hydrophobicity of NOM, and then presents a brief introduction of the methods which can prevent membrane fouling such as pretreatment of the feed water (e.g., coagulation, adsorption, and pre-oxidation and membrane hydrophilic modification (e.g., plasma modification, irradiation grafting modification, surface coating modification, blend modification, etc.. Perspectives of further research are also discussed.

  13. A New Concept of Ultrafiltration Fouling Control: Backwashing with Low Ionic Strength Water

    NARCIS (Netherlands)

    Li, S.

    2011-01-01

    Ultrafiltration (UF) is a proven technology in water treatment nowadays. However, fouling remains a major challenge in the operation of UF, especially in regard to colloidal NOM fouling. In general, a number of colloidal NOM fouling mechanisms may occur, such as adsorption, gel formation. Colloidal

  14. Grafting polymer brushes on biomimetic structural surfaces for anti-algae fouling and foul release.

    Science.gov (United States)

    Wan, Fei; Pei, Xiaowei; Yu, Bo; Ye, Qian; Zhou, Feng; Xue, Qunji

    2012-09-26

    Sylgard-184 silicone elastomer negative replica and resorcinol-formaldehyde (RF) positive replica were made by biomimicking the patterns of natural Trifolium and three other kinds of leaves using the micromolding lithography. An effective antifouling (AF) polymer, poly(3-sulfopropyl methacrylate) (PSPMA), was then grafted on these replica surfaces via the surface-initiated atom transfer radical polymerization (SI-ATRP). The AF property of the modified biomimetic surfaces was tested via the settlement assay with two microalgae in different sizes, and their fouling-release (FR) property was evaluated by the removal assay. The results indicate that the structure of microspines on Trifolium leaf can inhibit settlement of microalgae and facilitate the cell release. The AF property was improved by modification with PSPMA brushes.

  15. Measurement Methodology for Monitoring Fouling Resistance in Condenser of Chiller

    Institute of Scientific and Technical Information of China (English)

    YU Dan; GAN Li-si; CAO Yong

    2009-01-01

    This paper established an on-line monitoring model for fouling resistance of cooling water based on heat transfer theory,which was mainly applied to the fouling resistance test for condenser of chiller in operation,and the test requirements were presented.It proves that the load ratio of chiller has big influence on the test re-sult,and the best load ratio for test is the range of 80%~100%.A case has been executed to validate the mod-el's feasibility.

  16. Cleaning protocol for a FO membrane fouled in wastewater reuse

    KAUST Repository

    Valladares Linares, Rodrigo

    2013-05-30

    Forward osmosis (FO) is an emerging technology which can be applied in water reuse applications. Osmosis is a natural process that involves less energy consumption than reverse osmosis (RO), and therefore can be applied as a dilution process before low-pressure RO; it is expected to compete favourably against current advanced water reuse technologies that use microfiltration/ultrafiltration and RO. The focus of this research was to assess the efficiency of different cleaning procedures to remove fouling from the surface of a FO membrane during the operation of a submerged system working in FO-mode (active layer (AL) facing feed solution) intended for secondary wastewater effluent (SWWE) recovery, using seawater as draw solution (DS), which will be diluted and can further be fed to a low-pressure RO unit to produce fresh water. Natural organic matter (NOM) fouling was expected to affect the AL, while for the support layer (SL), transparent exopolymer particles (TEP) were used as indicators of fouling due to their stickiness and propensity to enhance the attachment of other foulants in seawater on the membrane surface. The composition of the NOM fouling layer was determined after proper characterisation with a liquid chromatograph coupled with organic carbon detection (LC-OCD), showing biopolymers and protein-like substances as the main constituents. NOM fouling showed high hydraulic reversibility after a 25% flux decline was observed, up to 89.5% when in situ air scouring for 15 min was used as a cleaning technique. Chemical cleaning with a mixture of Alconox, an industrial detergent containing phosphates, and sodium EDTA showed to increase the reversibility (93.6%). Osmotic backwash using a 4% NaCl solution and DI water proved to be ineffective to recover flux due to the salt diffusion phenomena occurring at the AL. Part of the flux that could not be recovered is attributable to TEP fouling on the SL, which forms clusters clearly identifiable with an optical

  17. Protein fouling in carbon nanotubes enhanced ultrafiltration membrane: Fouling mechanism as a function of pH and ionic strength

    KAUST Repository

    Lee, Jieun

    2016-11-04

    The protein fouling behavior was investigated in the filtration of the multiwall carbon nanotube (MWCNT) composite membrane and commercial polyethersulfone ultrafiltration (PES-UF) membrane. The effect of solution chemistry such as pH and ionic strength on the protein fouling mechanism was systematically examined using filtration model such as complete pore blocking, intermediate pore blocking and cake layer formation. The results showed that the initial permeate flux pattern and fouling behavior of the MWCNT composite membrane were significantly influenced by pH and ionic strength while the effect of PES-UF membrane on flux was minimal. In a lysozyme (Lys) filtration, the severe pore blocking in the MWCNT membrane was made by the combined effect of intra-foulant interaction (Lys-Lys) and electrostatic repulsion between the membrane surface and the foulant at pH 4.7 and 10.4, and increasing ionic strength where the foulant-foulant interaction and membrane-fouling interaction were weak. In a bovine serum albumin (BSA) filtration, severe pore blocking was reduced by less deposition via the electrostatic interaction between the membrane and foulant at pH 4.7 and 10.4 and increasing ionic strength, at which the interaction between the membrane and BSA became weak. For binary mixture filtration, the protein fouling mechanism was more dominantly affected by foulant-foulant interaction (Lys-BSA, Lys-Lys, and BSA-BSA) at pH 7.0 and increase in ionic strength. This research demonstrates that MWCNT membrane fouling can be alleviated by changing pH condition and ionic strength based on the foulant-foulant interaction and the electrostatic interaction between the membrane and foulant.

  18. Dynamics of the Fouling Layer Microbial Community in a Membrane Bioreactor.

    Directory of Open Access Journals (Sweden)

    Anja S Ziegler

    Full Text Available Membrane fouling presents the greatest challenge to the application of membrane bioreactor (MBR technology. Formation of biofilms on the membrane surface is the suggested cause, yet little is known of the composition or dynamics of the microbial community responsible. To gain an insight into this important question, we applied 16S rRNA gene amplicon sequencing with a curated taxonomy and fluorescent in situ hybridization to monitor the community of a pilot-scale MBR carrying out enhanced biological nitrogen and phosphorus removal with municipal wastewater. In order to track the dynamics of the fouling process, we concurrently investigated the communities of the biofilm, MBR bulk sludge, and the conventional activated sludge system used to seed the MBR system over several weeks from start-up. As the biofilm matured the initially abundant betaproteobacterial genera Limnohabitans, Hydrogenophaga and Malikia were succeeded by filamentous Chloroflexi and Gordonia as the abundant species. This study indicates that, although putative pioneer species appear, the biofilm became increasingly similar to the bulk community with time. This suggests that the microbial population in bulk water will largely determine the community structure of the mature biofilm.

  19. Nanoscale engineering of low-fouling surfaces through polydopamine immobilisation of zwitterionic peptides.

    Science.gov (United States)

    Cui, Jiwei; Ju, Yi; Liang, Kang; Ejima, Hirotaka; Lörcher, Samuel; Gause, Katelyn T; Richardson, Joseph J; Caruso, Frank

    2014-04-21

    We report a versatile approach for the design of substrate-independent low-fouling surfaces via mussel-inspired immobilisation of zwitterionic peptides. Using mussel-inspired polydopamine (PDA) coatings, zwitterionic glutamic acid- and lysine-based peptides were immobilised on various substrates, including noble metals, metal oxides, polymers, and semiconductors. The variation of surface chemistry and surface wettability upon surface treatment was monitored with X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. Following peptide immobilisation, the surfaces became more hydrophilic due to the strong surface hydration compared with PDA-coated surfaces. The peptide-functionalised surfaces showed resistance to human blood serum adsorption and also effectively prevented the adhesion of gram-negative and gram-positive bacteria (i.e., Escherichia coli and Staphylococcus epidermidis) and mammalian cells (i.e., NIH 3T3 mouse embryonic fibroblast cells). The versatility of mussel-inspired chemistry combined with the unique biological nature and tunability of peptides allows for the design of low-fouling surfaces, making this a promising coating technique for various applications.

  20. Evaluation of micropollutant removal and fouling reduction in a hybrid moving bed biofilm reactor-membrane bioreactor system.

    Science.gov (United States)

    Luo, Yunlong; Jiang, Qi; Ngo, Huu H; Nghiem, Long D; Hai, Faisal I; Price, William E; Wang, Jie; Guo, Wenshan

    2015-09-01

    A hybrid moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) system and a conventional membrane bioreactor (CMBR) were compared in terms of micropollutant removal efficiency and membrane fouling propensity. The results show that the hybrid MBBR-MBR system could effectively remove most of the selected micropollutants. By contrast, the CMBR system showed lower removals of ketoprofen, carbamazepine, primidone, bisphenol A and estriol by 16.2%, 30.1%, 31.9%, 34.5%, and 39.9%, respectively. Mass balance calculations suggest that biological degradation was the primary removal mechanism in the MBBR-MBR system. During operation, the MBBR-MBR system exhibited significantly slower fouling development as compared to the CMBR system, which could be ascribed to the wide disparity in the soluble microbial products (SMP) levels between MBBR-MBR (4.02-6.32 mg/L) and CMBR (21.78 and 33.04 mg/L). It is evident that adding an MBBR process prior to MBR treatment can not only enhance micropollutant elimination but also mitigate membrane fouling.

  1. Effect of oxygen on fouling behavior in lead bismuth coolant systems

    Science.gov (United States)

    Niu, Fenglei; Candalino, Robert; Li, Ning

    2007-06-01

    This experimental research investigates the effects of the oxygen in lead-bismuth eutectic on fouling. The analysis was carried out by performing three tests with different oxygen concentration on the recuperator where the heat transfer rate is susceptible to fouling, and introducing a correlation for the fouling factor. The comparison of fouling factors obtained with each oxygen level is presented, the relationship between fouling factors and oxygen concentrations is correlated, and the effects of oxidation on heat transfer are demonstrated qualitatively by wetting conditions of the samples.

  2. Temperature and body weight affect fouling of pig pens

    NARCIS (Netherlands)

    Aarnink, A.J.A.; Schrama, J.W.; Heetkamp, M.J.W.; Stefanowska, J.; Huynh, T.T.T.

    2006-01-01

    Fouling of the solid lying area in pig housing is undesirable for reasons of animal welfare, animal health, environmental pollution, and labor costs. In this study the influence of temperature on the excreting and lying behavior of growing-finishing pigs of different BW (25, 45, 65, 85, or 105 kg) w

  3. Electromagnetic anti-fouling technology for prevention of scale

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    An electromagnetic anti-fouling technology(EAFT) was developed further. The operating principle of the EAFT was presented using fundamental physics laws. To validate the effect of EAFT and identify the mechanism, a circulating flow setup was built. A series of fouling tests were carried out with and without EAFT, measuring fouling thermal resistance as function of time, making scanning electron microscope images and analyzing the particles size distribution in solution by dynamics light scattering technology. The main results were as follows: 1)All the precipitated crystals in solution were calcite and there were little differences between with EAFT and without EAFT in the experimental range. 2) The number of precipitate nucleation in solution was small and the particle growth was slow without EAFT. In opposition to the case untreated, a rapid particle growth was observed and the number of nucleation was expected to be large, due to the fact that the EAFT effectively increases the ions and crystals collision frequency and effectiveness by utilizing the induced electric field. It is indicated that the particle growth is promoted mainly by coagulation process but not nucleation growth. 3) The EAFT could prolong the delay time of fouling greatly, and after the delay time, the thermal resistance quickly increased. Therefore, in order to mitigate scale significantly, the floccules in solution should be deposited beforehand in a low-lying area of the exchangers and let off in time.

  4. Fouling acorn barnacles in China——a review

    Institute of Scientific and Technical Information of China (English)

    CAO Wenhao; YAN Tao; LI Zufu; LI Jing; CHENG Zhiqiang

    2013-01-01

    We review the species composition,distribution,and seasonal variation of fouling acorn barnacles in Chinese waters—from Bohai Sea and Yellow Sea to East and South China Seas.Thirty-two species of acorn barnacles were found,of which,the dominant species are Amphibalanus amphitrite,A.reticulatus,A.variegates,Balanus trigonus,Fistulobalanus kondakovi,Megabalanus tintinnabulum,Striatobalanus amaryllis,and Eurapha withersi in the fouling communities.A.amphitrite is the dominant species in the coastal waters of Bohai Sea and Yellow Sea and A.reticulatus is dominant in the East and South China Seas.The settlement period of fouling acorn barnacles is usually in summer and autumn.From north to south with the decrease of latitude,their settlement period obviously extends,even to the whole year,and the species number also increases.Other environmental factors,such as salinity and distance from shore,also play an important role in the distribution of fouling acorn barnacles.

  5. SINTESIS MEMBRAN ULTRAFILTRASI NON FOULING UNTUK APLIKASI PEMPROSESAN BAHAN PANGAN

    Directory of Open Access Journals (Sweden)

    Luqman Buchori

    2012-02-01

    Full Text Available Membran ultrafiltrasi (UF telah terbukti sebagai proses yang menjanjikan untuk aplikasi di bidang pemprosesan bahan pangan. Namun, peristiwa fouling dapat menurunkan kinerja membran secara signifikan. Meskipun banyak metode pengendalian fouling telah diusulkan, dalam banyak kasus kinerja proses sangat dipengaruhi oleh membran sebagai jantung dari proses. Dalam makalah ini pengendalian fouling dilakukan dengan memodifikasi permukaan membran dengan teknik kopolimerisasi foto-grafting. Acrylic acid (AA, acrylamido methylpropane sulfonic acid (AMPS, poly(ethylene glycol methacrylate (PEGMA, dan N,N-dimethyl-N-(2-methacryloyloxyethyl-N-(3sulfopropylammonium betaine sebagai senyawa zwitterion (ZI digunakan sebagai monomer fungsional. Pengaruh waktu iradiasi terhadap efektifitas modifikasi telah diamati. Kinerja membran hasil modifikasi kemudian diuji dengan menggunakan berbagai model larutan foulant yang meliputi larutan protein, larutan polisakarida dan larutan polifenol. Hasil penelitian menunjukkan bahwa sifat non fouling membran sangat jelas dapat ditingkatkan baik dengan PEGMA maupun dengan ZI. Secara umum, modifikasi menggunakan PEGMA menunjukkan kinerja yang lebih baik. Larutan polifenol menunjukkan karakter foulant yang paling kuat diantara model foulant.

  6. Reduced fouling of ultrafiltration membranes via surface fluorination

    Energy Technology Data Exchange (ETDEWEB)

    Sedath, R.H.; Yates, S.F.; Li, N.N.

    1993-03-01

    Surface fluorination can affect significantly the performance of an ultrafiltration membrane used to concentrate a food-related stream. Membranes fluorinated and tested as flat sheets exhibit higher initial fluxes, and do not foul as rapidly as untreated membranes. This improvement is linked to increased surface hydrophilicity, as shown in decreased contact angle with water. This increased hydrophilicity, in turn, is linked to the addition of fluorine and oxygen to the surface. The pilot plant study did-not show the difference in membrane flux and fouling observed in the flat sheet study. Instead, fluorinated and unfluorinated modules behaved similarly. Fouling by potato waste feed was severe and resulted in formation of an extensive gel layer within the module on the membrane surface. XPS, SEM and FTIR indicate that buildup of organic material occurred on both fluorinated and unfluorinated membranes, but SEM indicates that a fibrous mat of material was observed only on the nonfluorinated membrane. We conclude that in the pilot study, membrane fouling and gel formation were so extensive that the surface interaction effect was overwhelmed.

  7. An assessment of gas-side fouling in cement plants

    Science.gov (United States)

    Marner, W. J.

    1982-01-01

    The cement industry is the most energy-intensive industry in the United States in terms of energy cost as a percentage of the total product cost. An assessment of gas-side fouling in cement plants with special emphasis on heat recovery applications is provided. In the present context, fouling is defined as the buildup of scale on a heat-transfer surface which retards the transfer of heat and includes the related problems of erosion and corrosion. Exhaust gases in the cement industry which are suitable for heat recovery range in temperature from about 100 to 1300 K, are generally dusty, may be highly abrasive, and are often heavily laden with alkalies, sulfates, and chlorides. Particulates in the exhaust streams range in size from molecular to about 100 micrometers in diameter and come from both the raw feed as well as the ash in the coal which is the primary fuel used in the cement industry. The major types of heat-transfer equipment used in the cement industry include preheaters, gas-to-air heat exchangers, waste heat boilers, and clinker coolers. At the present time, the trend in this country is toward suspension preheater systems, in which the raw feed is heated by direct contact with the hot kiln exit gases, and away from waste heat boilers as the principal method of heat recovery. The most important gas-side fouling mechanisms in the cement industry are those due to particulate, chemical reaction, and corrosion fouling.

  8. CHEMICAL CLEANING OF NANOFILTRATION MEMBRANES FOULED BY ORGANIC MATTERS

    Directory of Open Access Journals (Sweden)

    CHARLENE C. H. KOO

    2016-07-01

    Full Text Available Membrane fouling is a term to describe non-integral substance on membrane surface which results in rapid decline of permeation flux and deteriorate the performance of membrane. Chemical cleaning agents especially like alkaline cleaners are most widely employed to restore the membrane performance. This research mainly investigated the potential use of sodium hydroxide (NaOH and sodium hypochlorite (NaOCl as the chemical cleaning agents to restore the permeate flux of organically fouled nanofiltration (NF membranes under varying applied pressure and flow condition. The performances of the cleaning protocols were quantified using flux recovery and resistance removal. The results demonstrated that NaOCl is more effective than NaOH. This observation is also in line with FTIR analysis in which the transmittance intensity showed by FTIR spectra of NaOCl is higher than that of NaOH. The results also reported that higher flux recovery and resistance removal were achieved when the fouled NF membranes were cleaned with higher concentration of chemical agents and applied pressure. However, the improvements of flux recovery and resistance removal by increasing the applied pressure were found insignificant at higher applied pressure range (16 to 18 bar than the lower applied pressure range (i.e. 12 to 14 bar. This research plays an important role by identifying the key parameters that could restore the flux of organically fouled NF membranes significantly.

  9. Influence of membrane properties on fouling in submerged membrane bioreactors

    NARCIS (Netherlands)

    Marel, van der P.; Zwijnenburg, A.; Kemperman, A.; Wessling, M.; Temmink, B.G.; Meer, van der W.

    2010-01-01

    Polymeric flat-sheet membranes with different properties were used in filtration experiments with activated sludge from a pilot-scale MBR to investigate the influence of membrane pore size, surface porosity, pore morphology, and hydrophobicity on membrane fouling. An improved flux-step method was us

  10. Water hammer reduces fouling during natural water ultrafiltration.

    Science.gov (United States)

    Broens, F; Menne, D; Pothof, I; Blankert, B; Roesink, H D W; Futselaar, H; Lammertink, R G H; Wessling, M

    2012-03-15

    Today's ultrafiltration processes use permeate flow reversal to remove fouling deposits on the feed side of ultrafiltration membranes. We report an as effective method: the opening and rapid closing of a valve on the permeate side of an ultrafiltration module. The sudden valve closure generates pressure fluctuations due to fluid inertia and is commonly known as "water hammer". Surface water was filtrated in hollow fiber ultrafiltration membranes with a small (5%) crossflow. Filtration experiments above sustainable flux levels (>125 l (m2h)(-1)) show that a periodic closure of a valve on the permeate side improves filtration performance as a consequence of reduced fouling. It was shown that this effect depends on flux and actuation frequency of the valve. The time period that the valve was closed proved to have no effect on filtration performance. The pressure fluctuations generated by the sudden stop in fluid motion due to the valve closure are responsible for the effect of fouling reduction. High frequency recording of the dynamic pressure evolution shows water hammer related pressure fluctuations to occur in the order of 0.1 bar. The pressure fluctuations were higher at higher fluxes (higher velocities) which is in agreement with the theory. They were also more effective at higher fluxes with respect to fouling mitigation.

  11. Self-Replenishing Vascularized Fouling-Release Surfaces

    Science.gov (United States)

    2014-01-01

    by generating a conditioning layer of proteins or polysaccharides to mask and condition the underlying surface.22,23 Fouling-release coatings are an...Webster, D. C. High Throughput Combinatorial Characterization of Thermosetting Silox- ane−urethane Coatings Having Spontaneously Formed Microtopo

  12. Temporal and spatial variation in the fouling of silicone coatings in Pearl Harbor, Hawaii.

    Science.gov (United States)

    Holm, E R; Nedved, B T; Phillips, N; Deangelis, K L; Hadfield, M G; Smith, C M

    2000-01-01

    An antifouling or foul-release coating cannot be globally effective if it does not perform well in a range of environmental conditions, against a diversity of fouling organisms. From 1996 to 1998, the field test sites participating in the United States Navy's Office of Naval Research 6.2 Biofouling program examined global variation in the performance of 3 silicone foul-release coatings, viz. GE RTV11, Dow Corning RTV 3140, and Intersleek (International Coatings Ltd), together with a control anticorrosive coating (Ameron Protective Coatings F-150 series). At the University of Hawaii's test site in Pearl Harbor, significant differences were observed among the coatings in the rate of accumulation of fouling. The control coating failed rapidly; after 180-220 d immersion a community dominated by molluscs and sponges developed that persisted for the remainder of the experiment. Fouling of the GE and Dow Corning silicone coatings was slower, but eventually reached a similar community structure and coverage as the control coatings. The Intersleek coating remained lightly fouled throughout the experiment. Spatial variation in the structure of the community fouling the coatings was observed, but not in the extent of fouling. The rate of accumulation of fouling reflected differences among the coatings in adhesion of the tubeworm Hydroides elegans. The surface properties of these coatings may have affected the rate of fouling and the structure of the fouling community through their influence on larval settlement and subsequent interactions with other residents, predators, and the physical environment.

  13. Membrane fouling mechanism transition in relation to feed water composition

    KAUST Repository

    Myat, Darli Theint

    2014-12-01

    The impact of secondary effluent wastewater from the Eastern Treatment Plant (ETP), Melbourne, Australia, before and after ion exchange (IX) treatment and polyaluminium chlorohydrate (PACl) coagulation, on hydrophobic polypropylene (PP) and hydrophilic polyvinylidene fluoride (PVDF) membrane fouling was studied. Laboratory fouling tests were operated over 3-5 days with regular, intermittent backwash. During the filtration with PP membranes, organic rejection data indicated that humic adsorption on hydrophobic PP membrane occurred during the first 24h of filtration and contributed to fouling for both raw wastewater and pre-treated wastewaters. However, after the first 24h of filtration the contribution of humic substances to fouling diminished and biopolymers that contribute to cake layer development became more prominent in their contribution to the fouling rate. For PVDF membranes, the per cent removal of humic substances from both raw wastewater and pre-treated wastewaters was very small as indicated by no change in UV254 from the feed to the permeate over the filtration period, even during the early stages of filtration. This suggested that the hydrophobic PP membrane adsorbed humic substances while the hydrophilic PVDF membrane did not. The highest mass of biopolymer removal by each PVDF membrane was from ETP water followed by PACl and IX treated water respectively. This was possibly due to differences in the backwashing efficiency linked to the filter cake contributed by biopolymers. Hydraulic backwashing was more effective during the later stages of filtration for the ETP water compared to IX and PACl treated waters, indicating that the filter cake contributed by ETP biopolymers was more extensively removed by hydraulic backwashing. It was proposed that humic substances may act to stabilise biopolymers in solution and that removing humics substances by coagulation or IX results in greater adhesive forces between the biopolymers and membrane/filter cake

  14. Analysis of fouling characteristic in enhanced tubes using multiple heat and mass transfer analogies☆

    Institute of Scientific and Technical Information of China (English)

    Zepeng Wang; Guanqiu Li; Jingliang Xu; Jinjia Wei; Jun Zeng; Decang Lou; Wei Li

    2015-01-01

    This paper provides a comprehensive analysis on cooling tower fouling data taken from seven 15.54 mm I.D. helically ribbed, copper tubes and a plain tube at Re=16000. There are two key processes during fouling formation:fouling deposition and fouling removal, which can be determined by mass transfer and fluid friction respectively. The mass transfer coefficient can be calculated through three analogies:Prandtl analogy, Von–Karman analogy, and Chilton–Colburn analogy. Based on our analyses, Von–Karman analogy is the optimized analogy, which can well predict the formation of cooling tower fouling. Series of semi-theoretical fouling correlations as a function of the product of area indexes and efficiency indexes were developed, which can be applicable to different internally ribbed geometries. The correlations can be directly used to assess the fouling potential of enhanced tubes in actual cooling tower water situations.

  15. Rejection of micropollutants by clean and fouled forward osmosis membrane.

    Science.gov (United States)

    Valladares Linares, Rodrigo; Yangali-Quintanilla, Victor; Li, Zhenyu; Amy, Gary

    2011-12-15

    As forward osmosis (FO) gains attention as an efficient technology to improve wastewater reclamation processes, it is fundamental to determine the influence of fouling in the rejection of emerging contaminants (micropollutants). This study focuses on the rejection of 13 selected micropollutants, spiked in a secondary wastewater effluent, by a FO membrane, using Red Sea water as draw solution (DS), differentiating the effects on the rejection caused by a clean and fouled membrane. The resulting effluent was then desalinated at low pressure with a reverse osmosis (RO) membrane, to produce a high quality permeate and determine the rejection with a coupled forward osmosis - low pressure reverse osmosis (FO-LPRO) system. When considering only FO with a clean membrane, the rejection of the hydrophilic neutral compounds was between 48.6% and 84.7%, for the hydrophobic neutrals the rejection ranged from 40.0% to 87.5%, and for the ionic compounds the rejections were between 92.9% and 96.5%. With a fouled membrane, the rejections were between 44.6% and 95.2%, 48.7%-91.5% and 96.9%-98.6%, respectively. These results suggest that, except for the hydrophilic neutral compounds, the rejection of the micropollutants is increased by the presence of a fouling layer, possibly due to the higher hydrophilicity of the FO fouled membrane compared to the clean one, the increased adsorption capacity of hydrophilic compounds and reduced mass transport capacity, membrane swelling, and the higher negative charge of the membrane surface, related to the foulants composition, mainly NOM acids (carboxylic radicals) and polysaccharides or polysaccharide-like substances. However, when coupled with RO, the rejections in both cases increased above 96%. The coupled FO-LPRO system was an effective double barrier against the selected micropollutants.

  16. Slagging and Fouling Characteristics of HRSG for Ferrosilicon Electric Furnaces

    Directory of Open Access Journals (Sweden)

    Yungang Wang

    2015-02-01

    Full Text Available The slagging and fouling characteristics of the heat recovery steam generator (HRSG for ferrosilicon electric furnaces are discussed in this paper. Three ash samples were taken from the HRSG of a ferrosilicon furnace in Ningxia Province, China, which suffered from serious slagging and fouling. X-ray fluorescence (XRF, X-ray powder diffraction (XRD and scanning electron microscope (SEM were used to analyze the ash samples. The results show that low melting point salt Na2SO4 and composite salts Na (AlSi3O8 and 3K2SO4·CaSO4 deposit on the superheater tube walls in aerosol form and solidify to form the initial slag layer. With the continuous deposition of the low melting point compounds, more and more ash particles in the flue gas adhere to the slag surface to form a thicker slag. Low melting point composite salt NaO·Al2O3·SiO2 is absorbed on the evaporator tube walls in aerosol form. With the deposition of NaO·Al2O3·SiO2, more and more ash particles are absorbed to form the fouling. Since there is less space between pin-finned tubes, the large iron-rich slag particles are easily deposited on tube walls and fin surfaces, which is advantageous to the fouling process. There are large quantities of superfine ash particles in the flue gas that easily adhere to other particles or tube walls, which facilitates the slagging and fouling process.

  17. Rejection of micropollutants by clean and fouled forward osmosis membrane

    KAUST Repository

    Valladares Linares, Rodrigo

    2011-12-01

    As forward osmosis (FO) gains attention as an efficient technology to improve wastewater reclamation processes, it is fundamental to determine the influence of fouling in the rejection of emerging contaminants (micropollutants). This study focuses on the rejection of 13 selected micropollutants, spiked in a secondary wastewater effluent, by a FO membrane, using Red Sea water as draw solution (DS), differentiating the effects on the rejection caused by a clean and fouled membrane. The resulting effluent was then desalinated at low pressure with a reverse osmosis (RO) membrane, to produce a high quality permeate and determine the rejection with a coupled forward osmosis - low pressure reverse osmosis (FO-LPRO) system. When considering only FO with a clean membrane, the rejection of the hydrophilic neutral compounds was between 48.6% and 84.7%, for the hydrophobic neutrals the rejection ranged from 40.0% to 87.5%, and for the ionic compounds the rejections were between 92.9% and 96.5%. With a fouled membrane, the rejections were between 44.6% and 95.2%, 48.7%-91.5% and 96.9%-98.6%, respectively. These results suggest that, except for the hydrophilic neutral compounds, the rejection of the micropollutants is increased by the presence of a fouling layer, possibly due to the higher hydrophilicity of the FO fouled membrane compared to the clean one, the increased adsorption capacity of hydrophilic compounds and reduced mass transport capacity, membrane swelling, and the higher negative charge of the membrane surface, related to the foulants composition, mainly NOM acids (carboxylic radicals) and polysaccharides or polysaccharide-like substances. However, when coupled with RO, the rejections in both cases increased above 96%. The coupled FO-LPRO system was an effective double barrier against the selected micropollutants. © 2011 Elsevier Ltd.

  18. Nanoparticle fouling and its combination with organic fouling during forward osmosis process for silver nanoparticles removal from simulated wastewater

    Science.gov (United States)

    Zhao, Yanxiao; Wang, Xinhua; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-05-01

    The increasing and wide application of silver nanoparticles (Ag NPs) has resulted in their appearance in wastewater. In consideration of their potential toxicity and environmental impacts, it is necessary to find effective technology for their removal from wastewater. Here, forward osmosis (FO) membrane was applied for Ag NPs removal from wastewater, and single and combined fouling of nanoparticles and organic macromolecules were further investigated during the FO process. The findings demonstrated that FO membrane can effectively remove Ag NPs from wastewater due to its high rejection performance. Fouling tests indicated that water flux declined appreciably even at the beginning of the single Ag NPs fouling test, and more remarkable flux decline and larger amounts of deposited Ag NPs were observed with an increase of Ag NPs concentration. However, the addition of bovine serum albumin (BSA) could effectively alleviate the FO membrane fouling induced by Ag NPs. The interaction between Ag NPs and BSA was responsible for this phenomenon. BSA can easily form a nanoparticle-protein corona surrounded nanoparticles, which prevented nanoparticles from aggregation due to the steric stabilization mechanism. Furthermore, the interaction between BSA and Ag NPs occurred not only in wastewater but also on FO membrane surface.

  19. Foul Play in Sport as a Phenomenon Inconsistent with the Rules, yet Acceptable and Desirable: Ethical Conditions

    Directory of Open Access Journals (Sweden)

    Kosiewicz Jerzy

    2014-06-01

    Full Text Available The article has strictly a theoretical and non-empirical character. The author presents examples resulting from various observations. The aim of the paper is to present the causes, functions, and results of fouls, fouling, and foul play. Although fouls do not comply with the rules of games, the paper demonstrates that fouls are often used; they enjoy a quiet acceptance of the sporting world; they are tolerated and accepted; even more, they are often - more or less explicitly - desirable.

  20. Impact of effluent organic matter on low-pressure membrane fouling in tertiary treatment

    KAUST Repository

    Ayache, C.

    2013-05-01

    This study aims at comparing low-pressure membrane fouling obtained with two different secondary effluents at bench and pilot-scale based on the determination of two fouling indices: the total fouling index (TFI) and the hydraulically irreversible fouling index (HIFI). The main objective was to investigate if simpler and less costly bench-scale experimentation can substitute for pilot-scale trials when assessing the fouling potential of secondary effluent in large scale membrane filtration plants producing recycled water. Absolute values for specific flux and total fouling index for the bench-scale system were higher than those determined from pilot-scale, nevertheless a statistically significant correlation (r2 = 0.63, α = 0.1) was obtained for the total fouling index at both scales. On the contrary no such correlation was found for the hydraulically irreversible fouling index. Advanced water characterization tools such as excitation-emission matrix fluorescence spectroscopy (EEM) and liquid chromatography with organic carbon detection (LC-OCD) were used for the characterization of foulants. On the basis of statistical analysis, biopolymers and humic substances were found to be the major contribution to total fouling (r2 = 0.95 and r2 = 0.88, respectively). Adsorption of the low molecular weight neutral compounds to the membrane was attributed to hydraulically irreversible fouling (r2 = 0.67). © 2013 Elsevier Ltd.

  1. Robust design optimization method for centrifugal impellers under surface roughness uncertainties due to blade fouling

    Science.gov (United States)

    Ju, Yaping; Zhang, Chuhua

    2016-03-01

    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  2. Biomimetic characterisation of key surface parameters for the development of fouling resistant materials.

    Science.gov (United States)

    Scardino, A J; Hudleston, D; Peng, Z; Paul, N A; de Nys, R

    2009-01-01

    Material science provides a direct route to developing a new generation of non-toxic, surface effect-based antifouling technologies with applications ranging from biomedical science to marine transport. The surface topography of materials directly affects fouling resistance and fouling removal, the two key mechanisms for antifouling technologies. However, the field is hindered by the lack of quantified surface characteristics to guide the development of new antifouling materials. Using a biomimetic approach, key surface parameters are defined and quantified and correlated with fouling resistance and fouling removal from the shells of marine molluscs. Laser scanning confocal microscopy was used to acquire images for quantitative surface characterisation using three-dimensional surface parameters, and field assays correlated these with fouling resistance and fouling release. Principle component analysis produced a major component (explaining 54% of total variation between shell surfaces) that correlated with fouling resistance. The five surface parameters positively correlated to increased fouling resistance were, in order of importance, low fractal dimension, high skewness of both the roughness and waviness profiles, higher values of isotropy and lower values of mean surface roughness. The second component (accounting for 20% of variation between shells) positively correlated to fouling release, for which higher values of mean waviness almost exclusively dictated this relationship. This study provides quantified surface parameters to guide the development of new materials with surface properties that confer fouling resistance and release.

  3. [Fouling behavior of sodium alginate during microfiltration at various ionic compositions: XDLVO approach].

    Science.gov (United States)

    Zhao, Ying-Xu; Zong, Rui-Qiang; Gao, Xin-Yu; Xie, Hui-Jun; Yin, Yong-Quan; Liang, Shuang

    2014-04-01

    The extended Derjaguin-Laudau-Verwey-Overbeek (XDLVO) theory was utilized to quantitatively evaluate short-range interfacial interactions involved in microfiltration (MF) membrane fouling by sodium alginate (SA) at various ionic compositions. Results showed that for hydrophilic membrane surfaces, van der Waals interactions facilitated fouling, whereas acid-base interactions alleviated fouling; for hydrophobic membrane surfaces, however, van der Waals interactions mitigated fouling and acid-base interactions turned out to be favorable for fouling. Electrostatic double layer interactions contributed minimally to fouling when SA molecules came into contact with MF membrane surface. Ionic strength and Ca2+ affected SA fouling of MF membranes mainly through alteration of acid-base interactions between membrane and SA or among SA themselves. Higher ionic strength could make acid-base interaction less repulsive or more attractive, thus aggravating SA fouling of MF membrane. Although Ca2+ accelerated flux decline significantly, Ca2+ could enhance physical cleaning efficiencies. Under all tested ionic compositions, fouling potentials (K) of initial and subsequent stages correlated well with membrane-SA interfacial free energy of adhesion and SA-SA interfacial free energy of cohesion, respectively. This implies that the XDLVO theory is applicable for description of MF membrane fouling by SA at various ionic compositions.

  4. Membrane fouling in pilot-scale membrane bioreactors (MBRs) treating municipal wastewater.

    Science.gov (United States)

    Kimura, Katsuki; Yamato, Nobuhiro; Yamamura, Hiroshi; Watanabe, Yoshimasa

    2005-08-15

    The main obstacle for wider use of membrane bioreactors (MBRs) for wastewater treatment is membrane fouling (i.e., deterioration of membrane permeability),which increases operating costs. For more efficient control of membrane fouling in MBRs, an understanding of the mechanisms of membrane fouling is important. However, there is a lack of information on membrane fouling in MBRs, especially information on features of components that are responsible for the fouling. We conducted a pilot-scale experiment using real municipal wastewater with three identical MBRs under different operating conditions. The results obtained in this study suggested that the food-microorganisms ratio (F/M) and membrane filtration flux were the important operating parameters that significantly influenced membrane fouling in MBRs. Neither concentrations of dissolved organic matter in the reactors nor viscosity of mixed liquor, which have been thought to have influences on fouling in MBRs, showed clear relationships with membrane fouling in this study. Organic substances that had caused the membrane fouling were desorbed from fouled membranes of the MBRs at the termination of the operation and were subjected to Fourier transform infrared (FTIR) and 13C nuclear magnetic resonance (NMR) analyses. These analyses revealed that the nature of the membrane foulant changes depending on F/M. It was shown that high F/M would make the foulant more proteinaceous. Carbohydrates were dominant in membrane foulants in this study, while features of humic substances were not apparent.

  5. Robust Design Optimization Method for Centrifugal Impellers under Surface Roughness Uncertainties Due to Blade Fouling

    Institute of Scientific and Technical Information of China (English)

    JU Yaping; ZHANG Chuhua

    2016-01-01

    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  6. Heat mass transfer model of fouling process of calcium carbonate on heat transfer surface

    Institute of Scientific and Technical Information of China (English)

    QUAN ZhenHua; CHEN YongChang; MA ChongFang

    2008-01-01

    A new heat mass transfer model was developed to predict the fouling process of calcium carbonate on heat transfer surface.The model took into account not only the crystallization fouling but also the particle fouling which was formed on the heat transfer surface by the suspension particles of calcium carbonate in the su-persaturated solution.Based on experimental results of the fouling process,the deposition and removal rates of the mixing fouling were expressed.Furthermore,the coupling effect of temperature with the fouling process was considered in the physics model.As a result the fouling resistance varying with time was obtained to describe the fouling process and the prediction was compared with experimental data under same conditions.The results showed that the present model could give a good prediction of fouling process,and the deviation was less than 15% of the experimental data in most cases.The new model is credible to predict the fouling process.

  7. Contribution of effluent organic matter (EfOM) to ultrafiltration (UF) membrane fouling: Isolation, characterization, and fouling effect of EfOM fractions

    KAUST Repository

    Zheng, Xing

    2014-11-01

    EfOM has been regarded as a major organic foulant resulting in UF membrane fouling in wastewater reclamation. To investigate fouling potential of different EfOM fractions, the present study isolated EfOM into hydrophobic neutrals (HPO-N), colloids, hydrophobic acids (HPO-A), transphilic neutrals and acids (TPI), and hydrophilics (HPI), and tested their fouling effect in both salt solution and pure water during ultrafiltration (UF). Major functional groups and chemical structure of the isolates were identified using Fourier transform infrared spectroscopy (FT-IR) and solid-state carbon nuclear magnetic resonance (13C NMR) analysis. The influence of the isolation process on the properties of EfOM fractions was minor because the raw and reconstituted secondary effluents were found similar with respect to UV absorbance, molecular size distribution, and fluorescence character. In membrane filtration tests, unified membrane fouling index (UMFI) and hydraulic resistance were used to quantify irreversible fouling potential of different water samples. Results show that under similar DOC level in feed water, colloids present much more irreversible fouling than other fractions. The fouling effect of the isolates is related to their size, chemical properties, and solution chemistry. Further investigations have identified that the interaction between colloids and other fractions also influences the performance of colloids in fouling phenomena. © 2014 Elsevier Ltd.

  8. Characteristics of heat transfer fouling of thin stillage using model thin stillage and evaporator concentrates

    Science.gov (United States)

    Challa, Ravi Kumar

    The US fuel ethanol demand was 50.3 billion liters (13.3 billion gallons) in 2012. Corn ethanol was produced primarily by dry grind process. Heat transfer equipment fouling occurs during corn ethanol production and increases the operating expenses of ethanol plants. Following ethanol distillation, unfermentables are centrifuged to separate solids as wet grains and liquid fraction as thin stillage. Evaporator fouling occurs during thin stillage concentration to syrup and decreases evaporator performance. Evaporators need to be shutdown to clean the deposits from the evaporator surfaces. Scheduled and unscheduled evaporator shutdowns decrease process throughput and results in production losses. This research were aimed at investigating thin stillage fouling characteristics using an annular probe at conditions similar to an evaporator in a corn ethanol production plant. Fouling characteristics of commercial thin stillage and model thin stillage were studied as a function of bulk fluid temperature and heat transfer surface temperature. Experiments were conducted by circulating thin stillage or carbohydrate mixtures in a loop through the test section which consisted of an annular fouling probe while maintaining a constant heat flux by electrical heating and fluid flow rate. The change in fouling resistance with time was measured. Fouling curves obtained for thin stillage and concentrated thin stillage were linear with time but no induction periods were observed. Fouling rates for concentrated thin stillage were higher compared to commercial thin stillage due to the increase in solid concentration. Fouling rates for oil skimmed and unskimmed concentrated thin stillage were similar but lower than concentrated thin stillage at 10% solids concentration. Addition of post fermentation corn oil to commercial thin stillage at 0.5% increments increased the fouling rates up to 1% concentration but decreased at 1.5%. As thin stillage is composed of carbohydrates, protein, lipid

  9. Worldwide genetic differentiation in the common fouling barnacle, Amphibalanus amphitrite

    KAUST Repository

    Chen, Hsi-Nien

    2014-10-21

    © 2014, © 2014 Taylor & Francis. Amphibalanus amphitrite is a common fouling barnacle distributed globally in tropical and subtropical waters. In the present study, the genetic (mitochondrial cytochrome oxidase subunit I) and morphological differentiation in A. amphitrite from 25 localities around the world were investigated. The results revealed three clades within A. amphitrite with a genetic divergence of ~ 4% among clades, whereas there were no diagnostic morphological differences among clades. Clade 1 is widely distributed in both temperate and tropical waters, whereas Clade 3 is currently restricted to the tropical region. The deep divergence among clades suggests historical isolation within A. amphitrite; thus, the present geographical overlaps are possibly a result of the combined effects of rising sea level and human-mediated dispersals. This study highlights the genetic differentiation that exists in a common, widely distributed fouling organism with great dispersal potential; future antifouling research should take into account the choice of lineages.

  10. A new concept for anti-fouling paint for Yachts

    DEFF Research Database (Denmark)

    Wallstroem, Eva; Jespersen, Henrik T.; Schaumburg, Kjeld

    2011-01-01

    -fouling products for yachts. To be able to reduce the amount of biocide, in this case zinc pyrithione, it is necessary to have control over the amount of biocide present in the surface layer. The control is achieved by encapsulating the biocide in a silica gel. The silica gel is dispersed together with pigments...... and fillers in the paint. The gel contributes to the polishing properties, where the gel particles are worn down throughout the polishing process. When a gel particle is opened by wear the biocide will be effective on the coating surface. It is also shown that zinc pyrithione is more efficient when...... it is encapsulated in a gel compared to a situation where it is not. This conclusion is based on the fact that the gel swells when exposed to water, and therefore the leach of zinc pyrithione is initially delayed and the biocide may start to solubilise and degrade. The result is an anti-fouling product...

  11. Characterization of a non-fouling ultrafiltration membrane

    DEFF Research Database (Denmark)

    Wei, J.; Helm, G.S.; Corner-Walker, N.

    2006-01-01

    -off (MWCO) were characterized by filtration studies using bovine serum albumin (BSA) and an enzyme solution as test media, and the membranes exhibited the non-fouling property. The surface chemistry of the unmodified and modified PVDF membranes was characterized by X-ray photoelectron spectroscopy (XPS...... surfaces was determined by the radio labeling technique. For the protein adsorption experiments, we have developed a method, which ensures that protein molecules only adsorb on the membrane surface, and that no adsorption on the pore walls of the porous sub-layer takes place.......This report describes the properties of surface-modified poly(vinylidene fluoride) (PVDF) membranes. These membranes were created by coating hydrophilic polymers on the support PVDF membrane to reduce the tendency to protein fouling. The modified membranes with different molecular weight cut...

  12. [Application of chemical ecology in controlling marine fouling organisms].

    Science.gov (United States)

    Fang, Fang; Yan, Tao; Liu, Qing

    2005-10-01

    Many marine organisms can produce secondary metabolites beneficial to the protection of marine environments against fouling, and thus, applying chemo-ecological methods to extract the natural antifoulants from marine organisms to resolve the problems relevant to marine fouling is a new thinking in resent years. Its aim is to search for high efficient and non-toxic antifoulants to replace the existing chemically synthetic ones which are unfortunately found to have widespread toxic effects on marine environment. Although we know few about the antifouling mechanisms of secondary metabolites, many natural products have been proved to have antifouling activity. Therefore, basic and applied researches on the ecological roles of these natural compounds, their action mechanisms, coating compatibility, controlled release, and field test are required in the future.

  13. Beer Clarification with polysulfone membrane and study on fouling mechanism

    Directory of Open Access Journals (Sweden)

    Ricardo Cardoso de Oliveira

    2011-12-01

    Full Text Available The aims of the present work were to study the relationship between the fluxes, permeate quality, and fouling mechanism. A polysulfone membrane with 100 KDa and 0.12 m² of surface area was used. Permeate fluxes were measured for different pressures (0.5, 1.0, 1.5, and 2.0 bar at the same temperature of 8 ºC. The fluxes measured for each pressure ranged from 22, 24, 27 and 30 kg h-1m-2 at 0.5, 1.0, 1.5 and 2.0 bar, respectively. Samples of the feed and permeate were analyzed for pH, color, turbidity, sugar, bitterness, and proteins. The fouling mechanisms observed were cake filtration, partial pore blocking, and complete pore blocking.

  14. Irreversible fouling during multicycle microfiltration of wastewater effluent.

    Science.gov (United States)

    Shan, Huifeng; Neufeld, Ronald D

    2007-12-01

    This study focused on irreversible fouling during microfiltration of primary and secondary effluents from municipal wastewater treatment plants. Flow resistances were calculated from the sum of clean membrane resistances, resultant cake layer resistances, and consequent irreversible fouling resistances. Results from a dead-end cell experimental system showed that the accumulated cake resistance was dominating for microfiltration of primary/secondary effluents. Suspended solids in the primary and secondary effluents had a similar compressibility index, n, with a value of approximately 0.5, indicating that they were moderately compressible particles. The value of irreversible resistance is dependent on the intensity of membrane cleaning; however, for a given membrane cleaning strategy, this value steadily increased and reached a maximum after approximately 6 cycles of filtration and cleaning. This study provided an explanation for the significant drop of throughput flux in the early application of membrane processes, and a plateau flux approached correspondingly.

  15. Membrane Fouling in Microfiltration used for Cell Harvesting

    Institute of Scientific and Technical Information of China (English)

    Tahereh Kaghazchi; Farzin Zokaee; Abbas Zare

    2001-01-01

    In the present study the membrane fouling in microfiltration used for cell harvesting in a deadend system has been investigated. Experimental results were analysed in terms of existing membrane filtration models and membrane resistances. The cake filtration model (CFM) and standard blocking model (SBM) have been considered in this study.Various membrane resistances were determined at different processing time, feed concentration and stirring speed. Resistances to permeation in this system include filter medium, pore blocking, adsorption, cake layer and concentration polarization.

  16. Membrane fouling in microfiltration used for cell harvesting

    Science.gov (United States)

    Kaghazchi, Tahereh; Zokaee, Farzin; Zare, Abbas

    2001-03-01

    In the present study the membrane fouling in microfiltration used for cell harvesting in a deadend system has been investigated. Experimental results were analysed in terms of existing membrane filtration models and membrane resistances. The cake filtration model (CFM) and standard blocking model (SBM) have been considered in this study. Various membrane resistances were determined at different processing time, feed concentration and stirring speed. Resistances to permeation in this system include filter medium, pore blocking, adsorption, cake layer and concentration polarization.

  17. Fouling-induced enzyme immobilization for membrane reactors

    DEFF Research Database (Denmark)

    Luo, Jianquan; Meyer, Anne S.; Jonsson, Gunnar Eigil

    2013-01-01

    , but the reverse mode allowed for higher enzyme loading and stability, and irreversible fouling (i.e. pore blocking) developed more readily in the support structure than in the skin layer. Compared with an enzymatic membrane reactor (EMR) with free enzymes, the novel EMR with enzymes immobilized in membrane...... support improved the enzyme reusability (especially for ADH), and reduced the product inhibition (especially for GDH). © 2013 Elsevier Ltd....

  18. Microscopic approach for the identification of cationic membrane fouling during cheddar cheese whey electroacidification.

    Science.gov (United States)

    Lin Teng Shee, F; Angers, P; Bazinet, L

    2008-06-15

    This is the first time that fouling of cation-exchange membranes during cheddar cheese whey electroacidification with bipolar membranes is reported. A mineral fouling was observed only on the cationic membrane side in contact with the base. The deposit was identified as magnesium hydroxide and this fouling was more important on the cation-exchange membrane situated close to the cathode. Little deposit was formed after six electroacidification runs, but on long time, the buildup of fouling film would lead after many electroacidifications to an important decrease of the system efficiency. Since, fouling of permselective membranes represents one of the major issues in electrodialytic processes, this result will be the basis for the determination of cleaning conditions allowing the prevention of such a fouling.

  19. The role of EPS in fouling and foaming phenomena for a membrane bioreactor.

    Science.gov (United States)

    Cosenza, Alida; Di Bella, Gaetano; Mannina, Giorgio; Torregrossa, Michele

    2013-11-01

    In contraposition to conventional activated sludge processes, the foaming phenomenon in membrane bioreactor (MBR) is still in its infancy. On the other hand, although several studies have been carried out for better understanding the fouling phenomenon in MBR there are still some gaps in the up-to-date knowledge. The extracellular polymeric substances (EPSs) may have a primary role in fouling and foaming phenomena which in turn can be crucial for MBRs. The aim of this study is to detect a possible relationship that EPSs may have with fouling and foaming in an MBR for wastewater treatment. Foaming phenomenon is monitored by performing specific foam-tests: Foam Power, Scum Index, Foam Rating and filamentous abundance. Results show a high correlation between fouling vs EPS and foaming vs bound EPSs. A relationship between foaming and fouling was also found: in general, when foaming occurred the fouling rate decreases because the EPS bound remained trapped in the floating scum.

  20. Fouling Issues in Membrane Bioreactors (MBRs for Wastewater Treatment: Major Mechanisms, Prevention and Control Strategies

    Directory of Open Access Journals (Sweden)

    Petros K. Gkotsis

    2014-10-01

    Full Text Available Membrane fouling is one of the most important considerations in the design and operation of membrane systems as it affects pretreatment needs, cleaning requirements, operating conditions, cost and performance. Given that membrane fouling represents the main limitation to membrane process operation, it is unsurprising that the majority of membrane material and process research and development conducted is dedicated to its characterization and amelioration. This work presents the fundamentals of fouling issues in membrane separations, with specific regard to membrane fouling in Membrane Bioreactors (MBRs and the most frequently applied preventive-control strategies. Feed pretreatment, physical and chemical cleaning protocols, optimal operation of MBR process and membrane surface modification are presented and discussed in detail. Membrane fouling is the major obstacle to the widespread application of the MBR technology and, therefore, fouling preventive-control strategies is a hot issue that strongly concerns not only the scientific community, but industry as well.

  1. Fouling-release Property of Water-filled Porous Elastomers

    Institute of Scientific and Technical Information of China (English)

    Lai-yong Xie; Fei Hong; Chuan-xin He; Jian-hong Liu; Chi Wu

    2012-01-01

    Since the fouling-releasing ability of silicone elastomers increased as their modulus decreases,we designed and prepared composites with embedded tiny NaCl crytals that were soluble after their immersion in water,resulting in water-filled porous elastomers.The scanning electron microscope images confirmed such a designed water-filling porous structure.The existence of many micro-drops of water in these specially designed elastomers decreased the shear storage modulus and increased the loss factors.The decrease of shear modulus plays a leading role here and is directly related to a lower critical peeling-off stress of a pseudo-barnacle on them.Therefore,such a novel preparation with cheap salts instead of an expensive silicone provides a better way to make fouling-release paints with a lower modulus,a lower critical peeling-off stress and a better fouling-release property without a significant decrease of the cross-linking density.

  2. Research and development to overcome fouling of membranes

    Energy Technology Data Exchange (ETDEWEB)

    Narang, S.C.; Sharma, S.K.; Ventura, S.C.; Roberts, D.L.; Ahner, N.

    1992-06-01

    During this first year of the program, we have successfully accomplished the main objective of demonstrating the feasibility of using piezoelectrically assisted ultrafiltration to reduce membrane fouling and enhance the flux through ultrafiltration membranes. A preliminary economic evaluation, accounting for the power consumption of the piezoelectric driver and the extent of permeate flow rate enhancement, has also shown that piezoelectrically assisted ultrafiltration is cost effective and economically competitive with traditional separation processes. Piezoelectric transducers, such as a piezoelectric lead zirconate titanate (PZT) disc or a piezoelectric horn, driven by moderate power, significantly enhance the permeate flux on fouled membranes, presumably because they promote local turbulence. Several experiments were conducted on polysulfone and regenerated cellulose UF membranes fouled during filtration of model feed solutions. Solutions of poly(ethylene glycol) and of high-molecular weight dextran were used as models. We found that we could significantly increase the permeate flux by periodically driving the piezoelectric transducer, horn, or PZT disc, by application of moderate power over short periods of time, from 20 to 90 seconds. Enhancements as high as a factor of 8 were recorded with a few seconds, and enhanced permeate fluxes were maintained over a prolonged period (up to 3 hours). The prolonged flux enhancement makes it feasible to drive the piezoelectric transducer intermittently, thereby reducing the power consumption of the piezoelectric driver.

  3. Desalination and water recovery: Control of membrane fouling

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, A.V.R.; Jagan Mohan, D.; Buch, P.R.; Joshi, S.V.; Pushpito Kumar Ghosh [Reverse Osmosis Discipline, Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat (India)]. E-mail: salt@csir.res.in

    2006-07-01

    Ultrafiltration (UF), Nanofiltration (NF) and Reverse Osmosis (RO) technologies are widely used for the production of safe drinking water, and for the recovery of reusable water from various industrial effluent streams. The most commonly encountered phenomenon in these processes, especially in water recovery application, is membrane fouling, and control of membrane fouling is regarded as a significant challenge. Membranes with charged and hydrophilic surfaces are reported to be less susceptible to fouling and often reversible. UF/RO membranes containing negatively charged and/or neutral hydrophilic functional groups on the surface were prepared by surface modification of suitable membranes. The surface modified membranes exhibited separations of 68%-85% for Na{sub 2}SO{sub 4}, 19%-31% for MgSO{sub 4}, 10%-26% for NaCl and 2%-12% for CaCl{sub 2} with water permeation rates of 9-50 l/m{sup 2}-h at the operating pressure of 4 kg/cm{sup 2}. The UF membranes were tested for water recovery from reactive dye effluents containing solutes with molecular sizes in the range of 600-1000 Da along with inorganic solutes. Surface-modified RO membranes were utilised for desalination of brackish water. (author)

  4. Novel filtration mode for fouling limitation in membrane bioreactors.

    Science.gov (United States)

    Wu, Jinling; Le-Clech, Pierre; Stuetz, Richard M; Fane, Anthony G; Chen, Vicki

    2008-08-01

    A novel filtration mode is presented to reduce fouling propensity in membrane bioreactors (MBR). During this mode, an elevated high instantaneous flux (60Lm(-2)h(-1)) is initially applied for a short time (120s), followed by a longer filtration (290s) at lower flux (10.3Lm(-2)h(-1)) and a backwash in each filtration cycle. The mixed mode is expected to limit irreversible fouling as the reversible fouling created during the initial stage appears to protect the membrane. Hydraulic performance and the components of foulants were analyzed and compared with conventional continuous and backwash modes. It was found that the mixed mode featured lower trans-membrane pressure (TMP) after 24h of filtration when compared to other modes. The mixed mode was effective in preventing soluble microbial products (SMP) attaching directly onto the membrane surface, keeping the cake layer weakly compressed, and reducing the mixed liquor suspended solids (MLSS) accumulation on the membrane. This strategy reduced the resistances of both the cake layer and the gel layer. A factorial experimental design was carried out for eight runs with different conditions to identify the major operational parameters affecting the hydraulic performances. The results showed that the value of the flux in the initial high-flux period had the most effect on the performance of the mixed mode: high initial flux (60Lm(-2)h(-1)) led to improved performance.

  5. Development of an on-line monitoring expert system for heating system fouling

    Science.gov (United States)

    Wang, Yuan-yuan; Wang, Jian-guo

    2008-12-01

    This paper intends to develop an on-line monitoring expert system for heating system fouling. It chooses pressure, flowing and temperature as basic diagnostic variables. The basic evaluative guide lines are the coefficient of flowing resistance, the efficiency and cost of heating system. This system can be used to monitor the fouling degrees and estimate the fouling positions. The expert system is programmed by Delphi to realize all functions.

  6. Prediction and mitigation of air preheater fouling due to ammonium bisulfate

    Energy Technology Data Exchange (ETDEWEB)

    Afonso, R.; Tavoulareas, S.; Stallings, J. [Energy and Environmental Strategies, MA (United States)

    2001-07-01

    This paper provides a brief review of the fundamentals of ammonium bisulfate (ABS) formation, deposition and fouling in the air preheater. It presents a software-based predictive model for assessing the potential for air preheater fouling as a result of proposed SNCR or SCR retrofits and considering site-specific conditions and introduces a software-based cost-benefit model for assessing the economic trade-offs of various ABS fouling mitigation options. 7 refs., 13 figs.

  7. Mathematical Modelling and Simulation of Fouling of Nigerian Crude Oil Equipment Installations

    OpenAIRE

    Abdulsalami S. KOVO

    2006-01-01

    The aim of this research work was to develop Mathematical Model to Predict the Fouling of Nigeria Oil Equipment Installation. The term fouling can defined as the deposition of unwanted material on heat transfer equipment, which results in an increase in thermal resistance to heat transfer and subsequent loss of equipment thermal efficiency. The modelling equation formulated was based on the principle of fouling process being in unsteady state condition. That is, the rate of deposition is not ...

  8. Particulate and organic matter fouling of seawater reverse osmosis systems: Characterization, modelling and applications

    OpenAIRE

    Salinas Rodriguez, S.G.

    2011-01-01

    Particulate/colloidal and organic fouling in seawater reverse osmosis (SWRO) systems results in flux decline, higher energy costs, increased salt passage, increased cleaning frequency, and use of chemicals. In practice, indices like SDI and MFI are used to assess particulate fouling, but they are performed at very high initial flux (> 1500 L/m2-h) and do not take into account the deposition of particles/colloids in RO systems. In this study, the Modified Fouling Index with ultrafiltration mem...

  9. Particulate and organic matter fouling of SWRO systems: Characterization, modelling and applications

    OpenAIRE

    Salinas Rodríguez, S.G.

    2011-01-01

    Particulate/colloidal and organic fouling in seawater reverse osmosis (SWRO) systems results in flux decline, higher energy costs, increased salt passage, increased cleaning frequency, and use of chemicals. In practice, indices like SDI and MFI are used to assess particulate fouling, but they are performed at very high initial flux (> 1500 L/m2-h) and do not take into account the deposition of particles/colloids in RO systems. In this study, the Modified Fouling Index with ultrafiltration mem...

  10. Tailoring Membrane Surface Charges: A Novel Study on Electrostatic Interactions during Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Daniel Breite

    2015-10-01

    Full Text Available In this work we aim to show that the overall surface potential is a key factor to understand and predict anti-fouling characteristics of a polymer membrane. Therefore, polyvinylidene fluoride membranes were modified by electron beam-induced grafting reactions forming neutral, acidic, alkaline or zwitterionic structures on the membrane surface. The differently charged membranes were investigated regarding their surface properties using diverse analytical methods: zeta potential, static and dynamic water contact angle, scanning electron microscopy (SEM and X-ray photoelectron spectroscopy (XPS. Porosimetry measurements proved that there is no pore blocking due to the modifications. Monodisperse suspensions of differently charged polystyrene beads were synthesized by a radical emulsion polymerization reaction and were used as a model fouling reagent, preventing comparability problems known from current literature. To simulate membrane fouling, different bead suspensions were filtered through the membranes. The fouling characteristics were investigated regarding permeation flux decline and concentration of model fouling reagent in filtrate as well as by SEM. By considering electrostatic interactions equal to hydrophobic interactions we developed a novel fouling test system, which enables the prediction of a membrane’s fouling tendency. Electrostatic forces are dominating, especially when charged fouling reagents are present, and can help to explain fouling characteristics that cannot be explained considering the surface wettability.

  11. Investigation of CaCO3 fouling in plate heat exchangers

    Science.gov (United States)

    Li, Wei; Zhou, Kan; Manglik, Raj M.; Li, Guan-Qiu; Bergles, Arthur E.

    2016-11-01

    An experimental investigation, coupled with theoretical modeling of CaCO3 fouling in plate-and-frame type heat exchangers (PHEs) have been conducted. Four different plates, made of SS-304, are used in two different surface patterns (chevron and zig-zag) of varying corrugation severity (waviness depth and pitch) and area enhancement. They were further characterized in clean, non-fouled convection by their measured heat transfer coefficients and friction factors in the Reynolds number range of 600-6000. The flow-fouling experiments delineate the effects of temperature and plate-surface geometry on growth rates and stabilization of fouling resistance, along with the anti-fouling behavior of plates coated with a hydrophobic PTFE (Teflon) film. Moreover, the microscopic structure of fouling deposits is mapped in a scanning-electron microscope. Corrugated plates with the largest height-to-pitch ratio and hydraulic diameter are found to have the lowest fouling growth rate and resistance; Teflon-film coating of plate surface is also found to mitigate fouling relative to the performance of bare stainless steel plates. Finally, a semi-empirical fouling model, based on the Prandtl-Taylor analogy, has been devised to describe the experimental data and provide a predictive tool.

  12. Membrane Bioreactor (MBR Technology for Wastewater Treatment and Reclamation: Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Oliver Terna Iorhemen

    2016-06-01

    Full Text Available The membrane bioreactor (MBR has emerged as an efficient compact technology for municipal and industrial wastewater treatment. The major drawback impeding wider application of MBRs is membrane fouling, which significantly reduces membrane performance and lifespan, resulting in a significant increase in maintenance and operating costs. Finding sustainable membrane fouling mitigation strategies in MBRs has been one of the main concerns over the last two decades. This paper provides an overview of membrane fouling and studies conducted to identify mitigating strategies for fouling in MBRs. Classes of foulants, including biofoulants, organic foulants and inorganic foulants, as well as factors influencing membrane fouling are outlined. Recent research attempts on fouling control, including addition of coagulants and adsorbents, combination of aerobic granulation with MBRs, introduction of granular materials with air scouring in the MBR tank, and quorum quenching are presented. The addition of coagulants and adsorbents shows a significant membrane fouling reduction, but further research is needed to establish optimum dosages of the various coagulants/adsorbents. Similarly, the integration of aerobic granulation with MBRs, which targets biofoulants and organic foulants, shows outstanding filtration performance and a significant reduction in fouling rate, as well as excellent nutrients removal. However, further research is needed on the enhancement of long-term granule integrity. Quorum quenching also offers a strong potential for fouling control, but pilot-scale testing is required to explore the feasibility of full-scale application.

  13. Assessment of Silt Density Index (SDI) as Fouling Propensity Parameter in Reverse Osmosis Desalination

    KAUST Repository

    Rachman, Rinaldi

    2011-07-01

    Reverse osmosis operations are facing persistent fouling phenomenon that has challenged the integrity of these processes. Prediction of fouling potential by measuring a fouling index toward feed water is essential to ensure robust operation. Moreover, employing a reliable fouling index with good reproducibility and precision is necessary. Silt density index (SDI) is considered insufficient in terms of reliability and empirical theory, among other limitations. Nevertheless due its simplicity, SDI measurement is utilized extensively in RO desalination systems. The aim of this research is to assess the reliability of SDI. Methods include the investigation of different SDI membranes and study of the nature of the SDI filtration. Results demonstrate the existence of the membrane properties\\' variation within manufacturers, which then causes a lack of accuracy in fouling risk estimation. The nature of particles during SDI filtration provides information that particle concentration and size play a significant role on SDI quantification with substantial representation given by particles with size close to membrane nominal pore size. Moreover, turbidity assisted SDI measurements along with determination of UF pretreated and clean water fouling potential, establishes the indication of non-fouling related phenomena involved on SDI measurement such as a natural organic matter adsorption and hydrodynamic condition that alters during filtration. Additionally, it was found that the latter affects the sensitivity of SDI by being represented by some portions of SDI value. Keywords: Reverse Osmosis, Fouling index, Particulate Fouling, Silt Density Index (SDI), and Assessment of SDI.

  14. Mathematical Modelling and Simulation of Fouling of Nigerian Crude Oil Equipment Installations

    Directory of Open Access Journals (Sweden)

    Abdulsalami S. KOVO

    2006-07-01

    Full Text Available The aim of this research work was to develop Mathematical Model to Predict the Fouling of Nigeria Oil Equipment Installation. The term fouling can defined as the deposition of unwanted material on heat transfer equipment, which results in an increase in thermal resistance to heat transfer and subsequent loss of equipment thermal efficiency. The modelling equation formulated was based on the principle of fouling process being in unsteady state condition. That is, the rate of deposition is not equal to the rate of removal. In other words, there is an accumulation. The final mathematical model developed representing the fouling of Nigeria Oil equipment was obtained as:... The correlation between the experimental and simulated result obtained using Average Absolute Deviation (A.A.D was between 0.0131 - 0.0201. The fluid temperature of 43°C and 63°C and wire temperature 200°C, 250°C and 300°C were the operating conditions for the investigation and prediction. The model was simulated using VISUAL BASIC 6.0 to predict the fouling behaviour. The results obtained showed that refinery Naptha fouls very heavily and this fouling decreases with increasing fluid and wire temperature. Fouling was very severe for wire temperature 200°C and fluid temperature 46°C. The main mechanism of fouling for refinery Naptha was chemical polymerization.

  15. Membrane Bioreactor (MBR) Technology for Wastewater Treatment and Reclamation: Membrane Fouling.

    Science.gov (United States)

    Iorhemen, Oliver Terna; Hamza, Rania Ahmed; Tay, Joo Hwa

    2016-01-01

    The membrane bioreactor (MBR) has emerged as an efficient compact technology for municipal and industrial wastewater treatment. The major drawback impeding wider application of MBRs is membrane fouling, which significantly reduces membrane performance and lifespan, resulting in a significant increase in maintenance and operating costs. Finding sustainable membrane fouling mitigation strategies in MBRs has been one of the main concerns over the last two decades. This paper provides an overview of membrane fouling and studies conducted to identify mitigating strategies for fouling in MBRs. Classes of foulants, including biofoulants, organic foulants and inorganic foulants, as well as factors influencing membrane fouling are outlined. Recent research attempts on fouling control, including addition of coagulants and adsorbents, combination of aerobic granulation with MBRs, introduction of granular materials with air scouring in the MBR tank, and quorum quenching are presented. The addition of coagulants and adsorbents shows a significant membrane fouling reduction, but further research is needed to establish optimum dosages of the various coagulants/adsorbents. Similarly, the integration of aerobic granulation with MBRs, which targets biofoulants and organic foulants, shows outstanding filtration performance and a significant reduction in fouling rate, as well as excellent nutrients removal. However, further research is needed on the enhancement of long-term granule integrity. Quorum quenching also offers a strong potential for fouling control, but pilot-scale testing is required to explore the feasibility of full-scale application.

  16. Understanding the risk of scaling and fouling in hollow fiber forward osmosis membrane application

    KAUST Repository

    Majeed, Tahir

    2016-06-23

    Fouling studies of forward osmosis (FO) were mostly conducted based on fouling evaluation principals applied to pressure membrane processes such as reverse osmosis (RO)/nanofiltration (NF)/microfiltration (MF)/ultrafiltration (UF). For RO/NF/MF/UF processes, the single flux driving force (hydraulic pressure) remains constant, thus the fouling effect is easily evaluated by comparing flux data with the baseline. Whilst, the scenario of fouling effects for FO process is entirely different from RO/NF/MF/UF processes. Continuously changing driving force (osmotic pressure difference), the changes in concentration polarization associated with the varying draw solution/feed solution concentration and the fouling layer effects collectively influence the FO flux. Thus, usual comparison of the FO flux outcome with the baseline results can not exactly indicate the real affect of membrane fouling, rather presents a misleading cumulative effect. This study compares the existing FO fouling technique with an alternate fouling evaluation approach using two FO set-ups. Scaling and fouling risk for hollow fiber FO was separately investigated using synthetic water samples and model organic foulants as alginate, humic acid and bovine serum albumin. Results indicated that FO flux declines up to 5% and 49% in active layer-feed solution and active layer-draw solution orientations respectively.

  17. Membrane Bioreactor (MBR) Technology for Wastewater Treatment and Reclamation: Membrane Fouling

    Science.gov (United States)

    Iorhemen, Oliver Terna; Hamza, Rania Ahmed; Tay, Joo Hwa

    2016-01-01

    The membrane bioreactor (MBR) has emerged as an efficient compact technology for municipal and industrial wastewater treatment. The major drawback impeding wider application of MBRs is membrane fouling, which significantly reduces membrane performance and lifespan, resulting in a significant increase in maintenance and operating costs. Finding sustainable membrane fouling mitigation strategies in MBRs has been one of the main concerns over the last two decades. This paper provides an overview of membrane fouling and studies conducted to identify mitigating strategies for fouling in MBRs. Classes of foulants, including biofoulants, organic foulants and inorganic foulants, as well as factors influencing membrane fouling are outlined. Recent research attempts on fouling control, including addition of coagulants and adsorbents, combination of aerobic granulation with MBRs, introduction of granular materials with air scouring in the MBR tank, and quorum quenching are presented. The addition of coagulants and adsorbents shows a significant membrane fouling reduction, but further research is needed to establish optimum dosages of the various coagulants/adsorbents. Similarly, the integration of aerobic granulation with MBRs, which targets biofoulants and organic foulants, shows outstanding filtration performance and a significant reduction in fouling rate, as well as excellent nutrients removal. However, further research is needed on the enhancement of long-term granule integrity. Quorum quenching also offers a strong potential for fouling control, but pilot-scale testing is required to explore the feasibility of full-scale application. PMID:27314394

  18. Membrane scouring to control fouling under fluidization of non-adsorbing media for wastewater treatment.

    Science.gov (United States)

    Aslam, Muhammad; Charfi, Amine; Kim, Jeonghwan

    2017-02-11

    Gas sparging is used as a traditional way to control membrane fouling in submerged membrane bioreactors (MBRs) in wastewater treatment. However, the gas sparging accounts for the largest fraction in operational cost to run the MBR systems. In this study, membrane fouling was controlled by integrating scouring media with gas sparging to reduce fouling rate at relatively low operational energy. Comparative study was performed using a fluidized membrane reactor treating synthetic feed solutions between polyethylene terephthalate (PET) scouring media (SM) fluidized by gas sparging (GS), liquid recirculation (LR), and combination of them to control membrane fouling. Addition of PET scouring media reduced the gas flow rate by 67% more with 30% less in fouling rate than gas sparing only. Combined usage of gas sparging and liquid recirculation to fluidize the PET scouring media (LR + GS + SM) showed 37% lower in fouling rate than that obtained by the scouring media fluidized by liquid recirculation (LR + SM) only through the reactor. The LR + GS + SM configuration reduced energy consumption by 90% more than that required by gas sparging alone. Mechanical cleaning driven by fluidizing PET scouring media could reduce membrane fouling due to removing deposit of inorganic particles from membrane surface effectively. However, the PET scouring media was not very effective to reduce membrane fouling caused by organic colloids which are expected to contribute pore fouling significantly.

  19. Identification of effluent organic matter fractions responsible for low-pressure membrane fouling

    KAUST Repository

    Filloux, Emmanuelle

    2012-11-01

    Anion exchange resin (AER), powder activated carbon (PAC) adsorption and ozonation treatments were applied on biologically treated wastewater effluent with the objective to modify the effluent organic matter (EfOM) matrix. Both AER and PAC led to significant total organic carbon (TOC) removal, while the TOC remained nearly constant after ozonation. Liquid Chromatography-Organic Carbon Detection (LC-OCD) analysis showed that the AER treatment preferentially removed high and intermediate molecular weight (MW) humic-like structures while PAC removed low MW compounds. Only a small reduction of the high MW colloids (i.e. biopolymers) was observed for AER and PAC treatments. Ozonation induced a large reduction of the biopolymers and an important increase of the low MW humic substances (i.e. building blocks).Single-cycle microfiltration (MF) and ultrafiltration (UF) tests were conducted using commercially available hollow fibres at a constant flux. After reconcentration to their original organic carbon content, the EfOM matrix modified by AER and PAC treatments exhibited higher UF membrane fouling compared to untreated effluent; result that correlated with the higher concentration of biopolymers. On the contrary, ozonation which induced a significant degradation of the biopolymers led to a minor flux reduction for both UF and MF filtration tests. Based on a single filtration, results indicate that biopolymers play a major role in low pressure membrane fouling and that intermediate and low MW compounds have minor impact. Thus, this approach has shown to be a valid methodology to identify the foulant fractions of EfOM. © 2012 Elsevier Ltd.

  20. Corrosion of metals and alloys - Corrosion and fouling in industrial cooling water systems - Part 1: Guidelines for conducting pilot-scale evaluation of corrosion and fouling control additives for open recirculating cooling water systems

    CERN Document Server

    International Organization for Standardization. Geneva

    2006-01-01

    Corrosion of metals and alloys - Corrosion and fouling in industrial cooling water systems - Part 1: Guidelines for conducting pilot-scale evaluation of corrosion and fouling control additives for open recirculating cooling water systems

  1. Fouling of Seawater Reverse Osmosis (SWRO) Membrane: Chemical and Microbiological Characterization

    KAUST Repository

    Khan, Muhammad T.

    2013-12-01

    In spite of abundant water resources, world is suffering from the scarcity of usable water. Seawater Reverse Osmosis (SWRO) desalination technology using polymeric membranes has been recognized as a key solution to water scarcity problem. However, economic sustainability of this advanced technology is adversely impacted by the membrane fouling problem. Fouling of RO membranes is a highly studied phenomenon. However, literature is found to be lacking a detailed study on kinetic and dynamic aspects of SWRO membrane fouling. The factors that impact the fouling dynamics, i.e., pretreatment and water quality were also not adequately studied at full–scale of operation. Our experimental protocol was designed to systematically explore these fouling aspects with the objective to improve the understanding of SWRO membrane fouling mechanisms. An approach with multiple analytical techniques was developed for fouling characterization. In addition to the fouling layer characterization, feed water quality was also analysed to assess its fouling potential. Study of SWRO membrane fouling dynamics and kinetics revealed variations in relative abundance of chemical and microbial constituents of the fouling layer, over operating time. Aromatic substances, most likely humic–like substances, were observed at relatively high abundance in the initial fouling layer, followed by progressive increase in relative abundances of proteins and polysaccharides. Microbial population grown on all membranes was dominated by specific groups/species belonging to different classes of Proteobacteria phylum; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age and with the position of membrane element in RO vessel. Our results demonstrated that source water quality can significantly impact the RO membrane fouling scenarios. Moreover, the major role of chlorination in the SWRO membrane fouling was highlighted. It was found that intermittent mode of chlorination

  2. Application of electrochemical processes to membrane bioreactors for improving nutrient removal and fouling control.

    Science.gov (United States)

    Borea, Laura; Naddeo, Vincenzo; Belgiorno, Vincenzo

    2017-01-01

    Membrane bioreactor (MBR) technology is becoming increasingly popular as wastewater treatment due to the unique advantages it offers. However, membrane fouling is being given a great deal of attention so as to improve the performance of this type of technology. Recent studies have proven that the application of electrochemical processes to MBR represents a promising technological approach for membrane fouling control. In this work, two intermittent voltage gradients of 1 and 3 V/cm were applied between two cylindrical perforated electrodes, immersed around a membrane module, at laboratory scale with the aim of investigating the treatment performance and membrane fouling formation. For comparison purposes, the reactor also operated as a conventional MBR. Mechanisms of nutrient removal were studied and membrane fouling formation evaluated in terms of transmembrane pressure variation over time and sludge relative hydrophobicity. Furthermore, the impact of electrochemical processes on transparent exopolymeric particles (TEP), proposed as a new membrane fouling precursor, was investigated in addition to conventional fouling precursors such as bound extracellular polymeric substances (bEPS) and soluble microbial products (SMP). All the results indicate that the integration of electrochemical processes into a MBR has the advantage of improving the treatment performance especially in terms of nutrient removal, with an enhancement of orthophosphate (PO4-P) and ammonia nitrogen (NH4-N) removal efficiencies up to 96.06 and 69.34 %, respectively. A reduction of membrane fouling was also observed with an increase of floc hydrophobicity to 71.72 %, a decrease of membrane fouling precursor concentrations, and, thus, of membrane fouling rates up to 54.33 %. The relationship found between TEP concentration and membrane fouling rate after the application of electrochemical processes confirms the applicability of this parameter as a new membrane fouling indicator.

  3. Implications of membrane fouling toward the removal of the pharmaceutical sulfamethoxazole by nanofiltration processes

    Institute of Scientific and Technical Information of China (English)

    Alexander SIMON; William PRICE; Long Duc NGHIEM

    2011-01-01

    The influence of membrane fouling on the retention of the trace organic contaminant sulfamethoxazole by a nanofiltration (NF) process was investigated.Organic fouling caused a severe flux decline possibly due to pore blocking and adsorption directly after the commencement of the fouling layer development.Such membrane-foulant interactions were absent for colloidal fouling,which resulted in a more gradual flux decline.Membrane charge played a significant role in the separation process of inorganic salts,where the retention was the highest in a caustic environment (high pH) due to more swollen membrane material caused by the higher negative charge on the membrane.Organic fouling and a combination of colloidal and organic fouling led to a significant increase in the membrane negative charge.The influence of membrane fouling on solute retention was dependent on the fouling behaviour and the physicochemical properties of the model foulants,where the model foulants probably contributed to an increase in the retention of charged solutes due to enhanced electrostatic interactions.Organic fouling caused an increase in the retention of inorganic salts and sulfamethoxazole due to pore blocking.In contrast,colloidal fouling caused a decrease in the retention of inorganic salts due to cake-enhanced concentration polarisation.However,the presence of a colloidal fouling layer did not reduce the retention of sulfamethoxazole.A mixture of colloidal and organic matter improved the retention of inorganic salts.A similar conclusion can be inferred for sulfamethoxazole at pH 4 when the compound exists in a neutral form.

  4. Real-time monitoring of biofoulants in a membrane bioreactor during saline wastewater treatment for anti-fouling strategies.

    Science.gov (United States)

    Tan, Songwen; Hou, Yang; Cui, Chunzhi; Chen, Xuncai; Li, Weiguo

    2017-01-01

    This work presents a novel, fast and simple monitoring-responding method at the very early stages of membrane bio-fouling in a membrane bioreactor (MBR) during saline wastewater treatment. The impacts of multiple environmental shocks on membrane fouling were studied. The transmembrane pressure exceeded the critical fouling pressure within 8days in the case of salinity shock or temperature shock. In the case of DO shock, the transmembrane pressure exceeded the critical fouling pressure after 16days, showing the lower impact of DO shock on the MBR. In another study, the membrane fouling was observed within 4days responding to mixed environmental shocks. To decrease the potential of membrane bio-fouling, another bioreactor was integrated immediately with the MBR as a quickly-responded countermeasure, when an early warning of membrane bio-fouling was provided. After the bioreactor enhancement, the time required for membrane fouling increased from 4 to 10days.

  5. Long-term performance and fouling analysis of full-scale direct nanofiltration (NF) installations treating anoxic groundwater

    KAUST Repository

    Beyer, Florian

    2014-10-01

    Long-term performance and fouling behavior of four full-scale nanofiltration (NF) plants, treating anoxic groundwater at 80% recovery for drinking water production, were characterized and compared with oxic NF and reverse osmosis systems. Plant operating times varied between 6 and 10 years and pretreatment was limited to 10μm pore size cartridge filtration and antiscalant dosage (2-2.5mgL-1) only. Membrane performance parameters normalized pressure drop (NPD), normalized specific water permeability (Kw) and salt retention generally were found stable over extended periods of operation (>6 months). Standard acid-base cleanings (once per year or less) were found to be sufficient to maintain satisfying operation during direct NF of the described iron rich (≤8.4mgL-1) anoxic groundwaters. Extensive autopsies of eight NF membrane elements, which had been in service since the plant startup (6-10 years), were performed to characterize and quantify the material accumulated in the membrane elements. Investigations using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), total organic carbon (TOC) and adenosine triphosphate (ATP) measurements revealed a complex mixture of organic, biological and inorganic materials. The fouling layers that developed during half to one year of operation without chemical cleaning were very thin (<2. μm). Most bio(organic) accumulates were found in the lead elements of the installations while inorganic precipitates/deposits (aluminosilicates and iron(II)sulfides) were found in all autopsied membrane elements. The high solubility of reduced metal ions and the very slow biofilm development under anoxic conditions prevented rapid fouling during direct NF of the studied groundwaters. When compared to oxic NF and RO systems in general (e.g. aerated ground waters or surface waters), the operation and performance of the described anoxic installations (with minimal pretreatment) can be described as very stable. © 2014

  6. Interplay of different NOM fouling mechanisms during ultrafiltration for drinking water production.

    Science.gov (United States)

    Jermann, D; Pronk, W; Meylan, S; Boller, M

    2007-04-01

    Ultrafiltration is an emerging technology for drinking water production, but a main challenge remains the lack of understanding about fouling. This paper investigates the impact of molecular interactions between different natural organic matter (NOM) compounds on ultrafiltration fouling mechanisms. We performed dead-end filtration experiments with individual and mixed humic acid and alginate (polysaccharide). Alginate showed detrimental, but mostly reversible, flux decline and high solute retention. Our results indicate that this was caused by pore blocking transformed into cake building and weak molecular foulant-membrane and foulant-foulant interactions. In the presence of calcium, aggravated fouling was observed, related to complexation of alginate and its subsequently induced gel formation. With humic acid, more severe irreversible fouling occurred due to humic acid adsorption. Minor adsorption of alginate onto the membrane was also observed, which probably caused the substantial irreversible flux decline. The fouling characteristics in the mixtures reflected a combination of the individual humic acid and alginate experiments and we conclude, that the individual fouling mechanisms mutually influence each other. A model elucidates this interplay of the individual fouling mechanisms via hydrophobic and electrostatic interactions. In our study such an interplay resulted in an alginate cake, or gel in the presence of calcium, which is relatively irreversibly adsorbed onto the membrane by humic acid associations. This study shows the importance of mutual influences between various foulants for improved understanding of fouling phenomena. Furthermore it shows that substances with a minor individual influence might have a large impact in mixed systems such as natural water.

  7. Particulate and organic matter fouling of seawater reverse osmosis systems: Characterization, modelling and applications

    NARCIS (Netherlands)

    Salinas Rodriguez, S.G.

    2011-01-01

    Particulate/colloidal and organic fouling in seawater reverse osmosis (SWRO) systems results in flux decline, higher energy costs, increased salt passage, increased cleaning frequency, and use of chemicals. In practice, indices like SDI and MFI are used to assess particulate fouling, but they are pe

  8. Particulate and organic matter fouling of SWRO systems: Characterization, modelling and applications

    NARCIS (Netherlands)

    Salinas Rodríguez, S.G.

    2011-01-01

    Particulate/colloidal and organic fouling in seawater reverse osmosis (SWRO) systems results in flux decline, higher energy costs, increased salt passage, increased cleaning frequency, and use of chemicals. In practice, indices like SDI and MFI are used to assess particulate fouling, but they are pe

  9. Workshop on an Assessment of Gas-Side Fouling in Fossil Fuel Exhaust Environments

    Science.gov (United States)

    Marner, W. J. (Editor); Webb, R. L. (Editor)

    1982-01-01

    The state of the art of gas side fouling in fossil fuel exhaust environments was assessed. Heat recovery applications were emphasized. The deleterious effects of gas side fouling including increased energy consumption, increased material losses, and loss of production were identified.

  10. Studies on fouling diatoms from the Zuari Estuary, Goa (west coast of India)

    Digital Repository Service at National Institute of Oceanography (India)

    Redekar, P.D.; Wagh, A.B.

    Very few studies are available in density of fouling diatoms from Zuari estuary, Goa, India. Hence this work was undertaken. In all 49 species of fouling diatoms belonging to 19 genera were recorded on glass slide as panels at 1 m depth in Zuari...

  11. The Influence of Unsportsmanlike Fouls on Basketball Teams' Performance According to Context-Related Variables.

    Science.gov (United States)

    Gómez, Miguel-Ángel; Toro, Enrique Ortega; Furley, Philip

    2016-07-01

    The aim of the current study was to analyze the temporal effects that unsportsmanlike fouls may have on basketball teams' scoring performance under consideration of context-related variables. The authors analyzed 130 unsportsmanlike fouls from 362 elite basketball games (men's and women's Olympic Games, European and World Championships). The context-related variables studied were score-line, quality of opposition, timeout situation, minutes remaining, and player status. The data were analyzed with linear-regression models. The results showed that both teams (the team that made the foul and the opponent) had similar positive scoring performances during 1 and 3 ball possessions after the unsportsmanlike foul (short-term effect). However, 5 ball possessions after the foul (midterm effect), the team that made the foul had a scoring disadvantage (-0.96) and the opponent team an advantage (0.78). The context-related variable quality of opposition was significant only during 1 ball possession, with negative effects for the team that made the foul and positive effects for the opponent. The final outcome showed a positive effect for score-line when the unsportsmanlike foul was made (0.96) and for quality of opposition (0.64).

  12. Genotypic variation in tolerance and resistance to fouling in the brown alga Fucus vesiculosus.

    Science.gov (United States)

    Honkanen, Tuija; Jormalainen, Veijo

    2005-06-01

    In this study, we examined genetic variation in resistance and tolerance to fouling organisms in the brown alga Fucus vesiculosus. We first grew 30 algal genotypes in the field, where we allowed fouling organisms to colonise the genotypes at natural levels. We then conducted a manipulative experiment, where we grew 20 genotypes of algae in aquaria with or without fouling organisms. We measured host resistance as the load of fouling organisms and tolerance as the slope of the regression of algal performance on fouling level. Fouling organisms decreased host growth and contents of phlorotannins and thus have the potential to act as selective agents on algal defenses. We found significant among-genotype variation in both resistance and tolerance to fouling. We did not find a trade-off between resistance and tolerance. We found a marginally significant cost of resistance, but no cost of tolerance. Our results thus indicate that both the tolerance and resistance of F. vesiculosus can evolve as a response to fouling and that the costs of resistance may maintain genetic variation in resistance.

  13. Costs and benefits to European shipping of ballast-water and hull-fouling treatment

    NARCIS (Netherlands)

    Fernandes, Jose A.; Santos, Lionel; Vance, Thomas; Fileman, Tim; Smith, David; Bishop, John D.D.; Viard, Frédérique; Queirós, Ana M.; Merino, Gorka; Buisman, Erik; Austen, Melanie C.

    2016-01-01

    Maritime transport and shipping are impacted negatively by biofouling, which can result in increased fuel consumption. Thus, costs for fouling reduction can be considered an investment to reduce fuel consumption. Anti-fouling measures also reduce the rate of introduction of non-indigenous species

  14. Fouling of microfiltration membranes by organic polymer coagulants and flocculants: controlling factors and mechanisms.

    Science.gov (United States)

    Wang, Sen; Liu, Charles; Li, Qilin

    2011-01-01

    Organic polymers are commonly used as coagulants or flocculants in pretreatment for microfiltration (MF). These high molecular weight compounds are potential membrane foulants when carried over to the MF filters. This study examined fouling of three MF membranes of different materials by three commonly used water treatment polymers: poly(diallyldimethylammonium) chloride (pDADMAC), polyacrylamide (PAM), and poly(acrylic acid-co-acrylamide (PACA) with a wide range of molecular weights. The effects of polymer molecular characteristics, membrane surface properties, solution condition and polymer concentration on membrane fouling were investigated. Results showed severe fouling of microfiltration membranes at very low polymer concentrations, suggesting that residual polymers carried over from the coagulation/flocculation basin can contribute significantly to membrane fouling. The interactions between polymers and membranes depended strongly on the molecular size and charge of the polymer. High molecular weight, positively charged polymers caused the greatest fouling. Blockage of membrane pore openings was identified as the main fouling mechanism with no detectable internal fouling in spite of the small molecular size of the polymers relative to the membrane pore size. Solution conditions (e.g., pH and calcium concentration) that led to larger polymer molecular or aggregate sizes resulted in greater fouling.

  15. Fouling of microfiltration membranes by flowback and produced waters from the Marcellus shale gas play.

    Science.gov (United States)

    Xiong, Boya; Zydney, Andrew L; Kumar, Manish

    2016-08-01

    There is growing interest in possible options for treatment or reuse of flowback and produced waters from natural gas processing. Here we investigated the fouling characteristics during microfiltration of different flowback and produced waters from hydraulic fracturing sites in the Marcellus shale. All samples caused severe and highly variable fouling, although there was no direct correlation between the fouling rate and total suspended solids, turbidity, or total organic carbon. Furthermore, the fouling of water after prefiltration through a 0.2 μm membrane was also highly variable. Low fouling seen with prefiltered water was mainly due to removal of submicron particles 0.4-0.8 μm during prefiltration. High fouling seen with prefiltered water was mainly caused by a combination of hydrophobic organics and colloidal particles membranes. The small colloidal particles were highly stable, likely due to the surfactants and other organics present in the fracking fluids. The colloid concentration was as high as 10(11) colloids/ml, which is more than 100 times greater than that in typical seawater. Furthermore, these colloids were only partially removed by MF, causing substantial fouling during a subsequent ultrafiltration. These results clearly show the importance of organics and colloidal material in membrane fouling caused by flowback and produced waters, which is of critical importance in the development of more sustainable treatment strategies in natural gas processing.

  16. Contribution of different effluent organic matter fractions to membrane fouling in ultrafiltration of treated domestic wastewater

    KAUST Repository

    Zheng, Xing

    2012-12-01

    In the present work, effluent organic matter (EfOM) in treated domestic wastewater was separated into hydrophobic neutrals, colloids, hydrophobic acids, transphilic acids and neutrals and hydrophilic compounds. Their contribution to dissolved organic carbon (DOC) was identified. Further characterization was conducted with respect to molecular size and hydrophobicity. Each isolated fraction was dosed into salt solution to identify its fouling potential in ultrafiltration (UF) using a hydrophilized polyethersulfone membrane. The results show that each kind of EfOM leads to irreversible fouling. At similar delivered DOC load to the membrane, colloids present the highest fouling effect in terms of both reversible and irreversible fouling. The hydrophobic organics show much lower reversibility than the biopolymers present. However, as they are of much smaller size than the membrane pore opening, they cannot lead to such severe fouling as biopolymers do. In all of the isolated fractions, hydrophilics show the lowest fouling potential. For either colloids or hydrophobic substances, increasing their content in feedwater leads to worse fouling. The co-effect between biopolymers and other EfOM fractions has also been identified as one of the mechanisms contributing to UF fouling in filtering EfOM-containing waters. © IWA Publishing 2012.

  17. Microbial Fouling and Its Effect on Power Generation.

    Science.gov (United States)

    1983-07-01

    t VI-4 iLndicates the influence of shear stress on- flui~d frictional resistance changes - caused by biof ilin aCCuAmulation. (Turakhia, unpublished...instrUment to test the performac:e of the eqUipment. The extent of the problem is determied and a FOULING CONTROL PREVENTION TREATMENT is applied. Any change ...examiple, some specific change mi.y signal the shUtdown of manulfa-cturing operations aind the beginri: ng of cleaning operations. The time required

  18. Research and development to overcome fouling of membranes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Narang, S.C.; Sharma, S.K.; Hum, G.; Ventura, S.C.; Roberts, D.L.; Gottschlich, D.; Ahner, N.

    1998-11-01

    To overcome fouling of membranes, SRI International is developing a unique piezoelectric backing for ultrafiltration membranes. This backing is capable of producing local turbulence next to the membrane to minimize concentration polarization and the rate of buildup of solutes and particulate matter on the membrane surface. We have studied piezoelectrically assisted ultrafiltration in more detail, with the objective to apply this process to industrial ultrafiltrations. We conducted several ultrafiltration experiments on flat sheet membranes with model dextran solutions and with electrocoat paint to study flux enhancement as a function of parameters such as feed flow rate, feed pressure, as well as the piezodriver-membrane system.

  19. Fundamentals of membrane bioreactors materials, systems and membrane fouling

    CERN Document Server

    Ladewig, Bradley

    2017-01-01

    This book provides a critical, carefully researched, up-to-date summary of membranes for membrane bioreactors. It presents a comprehensive and self-contained outline of the fundamentals of membrane bioreactors, especially their relevance as an advanced water treatment technology. This outline helps to bring the technology to the readers’ attention, and positions the critical topic of membrane fouling as one of the key impediments to its more widescale adoption. The target readership includes researchers and industrial practitioners with an interest in membrane bioreactors.

  20. Behavior of geogrid-reinforced ballast under various levels of fouling

    Energy Technology Data Exchange (ETDEWEB)

    Indraratna, B.; Ngo, T.; Rujikiatkamjorn, C. [University of Wollongong, Wollongong, NSW (Australia)

    2011-06-15

    This paper presents a study of how the interface between ballast and geogrid copes with fouling by coal fines. The stress-displacement behavior of fresh and fouled ballast, and geogrid reinforced ballast was investigated through a series of large-scale direct shear tests where the levels of fouling ranged from 0% to 95% Void Contamination Index (VCI), at relatively low normal stresses varying from 15 kPa to 75 kPa. The results indicated that geogrid increases the shear strength and apparent angle of shearing resistance, while only slightly reducing the vertical displacement of the composite geogrid-ballast system. However, when ballast was fouled by coal fines, the benefits of geogrid reinforcement decreased in proportion to the increasing level of fouling. A conceptual normalized shear strength model was proposed to predict this decrease in peak shear stress and peak angle of shearing resistance caused by coal fines at a given normal stress.

  1. Mitigating fouling in the high temperature paraffinic froth treatment process through science and serendipity

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarty, Tapantosh [Imperial Oil Resources (Canada)], email: apan.chakrabarty@esso.ca

    2010-07-01

    This work focuses on the application of high temperature paraffinic froth treatment (HT-PFT); a technique used to clean froth that results from the process of water extraction of oil sands. This technique includes the addition of a paraffinic solvent to the bitumen as a preliminary step in removing froth structures, leading to a possible fouling of the inner walls of the treatment vessels. Therefore, a fouling preventive technique consisting of three novel solutions was investigated in this work. The accumulations of fouling components were constantly monitored during the HT-PFT process using a gamma-ray densitometer. Results showed that buildups mostly consisted of inorganic solid structures held together with asphaltene. It was also shown that fluorocarbon polymer coating (FPC) proved to be the most effective additive in preventing fouling buildups, and by using fouling collectors in the vessels buildups were highly reduced downstream. In general, incorporating this preventive technique with HT-PFT was recommended.

  2. Dynamic fouling behaviors of submerged nonwoven bioreactor for filtration of activated sludge with different SRT.

    Science.gov (United States)

    Chuang, Shun-Hsing; Lin, Po-Kuen; Chang, Wei-Chin

    2011-09-01

    The flux variations and resistances accumulated during filtration of activated sludge with sludge retention time (SRT) of 15, 30, and 60 days were analyzed to investigate the dynamic fouling behavior in a submerged nonwoven bioreactor. Different SRT values varied sludge condition and particle size distribution in the supernatants, which caused dissimilar fouling characteristics. Short-term fouling of the nonwoven bioreactor during filtration of activated sludge with SRT of 15 days was fully reversible, and the resistance percentages of solutes, colloids, and suspended solids were 6%, 27%, and 67%, respectively. On the other hand, significant increases of colloid resistance, such as with the filtration of activated sludge with SRT of 30 and 60 days, were related to the occurrence of irreversible fouling. The phenomenon of pore blocking by particles or colloids with size analogous to the pore of nonwoven fabric was a decisive factor leading to irreversible fouling in the large-pore materials.

  3. Compressibility of the fouling layer formed by membrane bioreactor sludge and supernatant

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Poorasgari, Eskandar; Christensen, Morten Lykkegaard

    the pressure range 0.08 - 0.13 bar. The fouling layer resistance increased while fouling layer compression was reversible. Conversely, the supernatant filtrations showed that the gel layer is compressible within the range 0.1 - 2 bar applied pressure. Calculated resistance of the gel layer indicated....... Compressibility of the gel layer was studied in a dead-end filtration system, whereas the compressibility of a fouling layer formed by MBR sludge was studied in a submerged system hollow sheet membrane by TMP stepping. It was shown that the fouling layer formed by the MBR sludge was highly compressible within...... that higher pressure causes higher change in resistance. The results of the gel compression study showed a lower compressibility of gel layers than the fouling layer formed by sludge flocs. At pressures between 0.1 to 0.5 bar there was no significant change in specific cake resistance with pressure compared...

  4. Hydrophilic fraction of natural organic matter causing irreversible fouling of microfiltration and ultrafiltration membranes.

    Science.gov (United States)

    Yamamura, Hiroshi; Okimoto, Kenji; Kimura, Katsuki; Watanabe, Yoshimasa

    2014-05-01

    Although membrane filtration is a promising technology in the field of drinking water treatment, persistent membrane fouling remains a major disadvantage. For more efficient operation, causative agents of membrane fouling need to be identified. Membrane fouling can be classified into physically reversible and irreversible fouling on basis of the removability of the foulants by physical cleaning. Four types of natural organic matter (NOM) in river water used as a source of drinking water were fractionated into hydrophobic and hydrophilic fractions, and their potential to develop irreversible membrane fouling was evaluated by a bench-scale filtration experiment together with spectroscopic and chromatographic analyses. In this study, only dissolved NOM was investigated without consideration of interactions of NOM fractions with particulate matter. Results demonstrated that despite identical total organic carbon (TOC), fouling development trends were significantly different between hydrophilic and hydrophobic fractions. The hydrophobic fractions did not increase membrane resistance, while the hydrophilic fractions caused severe loss of membrane permeability. These results were identical with the case when the calcium was added to hydrophobic and hydrophilic fractions. The largest difference in NOM characteristics between hydrophobic and hydrophilic fractions was the presence or absence of macromolecules; the primary constituent causing irreversible fouling was inferred to be "biopolymers", including carbohydrates and proteins. In addition, the results demonstrated that the extent of irreversible fouling was considerably different depending on the combination of membrane materials and NOM characteristics. Despite identical nominal pore size (0.1 μm), a polyvinylidene fluoride (PVDF) membrane was found to be more rapidly fouled than a PE membrane. This is probably explained by the generation of strong hydrogen bonding between hydroxyl groups of biopolymers and fluorine

  5. Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

    Institute of Scientific and Technical Information of China (English)

    DONG Bing-zhi; CHEN Yan; GAO Nai-yun; FAN Jin-chu

    2007-01-01

    The purpose of this study is to understand the effect and mechanism of preventing membrane fouling,by coagulation pretreatment,in terms of fractional component and molecular weight of natural organic matter(NOM).A relatively higher molecular weight(MW)of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux.Coagulation could effectively remove the hydrophobic organics.resulting in the increase of flux.It was found that a lower MW of neutral hydrophilic compounds,which could remove inadequately by coagulation.was responsible for tlle slow declining flux.The fluxes in the filtration of coagulated water and supematant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane,resulting in fouling.It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively.Therefore,with the coagulated flocs formed on the membrane surface,the flux decline could be improved.

  6. EVALUASI KINERJA HEAT EXCHANGER DENGAN METODE FOULING F

    Directory of Open Access Journals (Sweden)

    Bambang Setyoko

    2012-02-01

    Full Text Available The performance of heat exchangers usually deteriorates with time as a result of accumulation of depositson heat transfer surfaces. The layer of deposits represents additional resistance to heat transfer and causesthe rate of heat transfer in a heat exchanger to decrease. The net effect of these accumulations on heattransfer is represented by a fouling factor Rf , which is a measure of the thermal resistance introduced byfouling.In this case, the type of fouling is the precipitation of solid deposits in a fluid on the heat transfer surface.The mineral deposits forming on the inner and the outer surfaces of fine tubes in the heat exchanger. Thefouling factor is increases with time as the solid deposits build up on the heat exchanger surface. Foulingincreases with increasing temperature and decreasing velocity.In this research, we obtain the coefisien clean overal 5,93 BTU/h.ft2.oF, Dirt factor 0,004 BTU/h.ft2 0F,Pressure drope in tube 2,84 . 10-3 Psi and pressure drope in shell 4,93 . 10-4 Psi.This result are less thanthe standard of parameter. Its means this Heat exchanger still clean relativity and can operate continousslywithout cleaning.

  7. Self-replenishing vascularized fouling-release surfaces.

    Science.gov (United States)

    Howell, Caitlin; Vu, Thy L; Lin, Jennifer J; Kolle, Stefan; Juthani, Nidhi; Watson, Emily; Weaver, James C; Alvarenga, Jack; Aizenberg, Joanna

    2014-08-13

    Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectious bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella salina, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.

  8. Mechanism of calcium mitigating membrane fouling in submerged membrane bioreactors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hanmin; XIA Jie; YANG Yang; WANG Zixing; YANG Fenglin

    2009-01-01

    Two parallel membrane bioreactors (MBRs) were operated under different calcium dosages (168.5, 27 mg/L) to gain a better understanding of the mechanism of retarding membrane fouling by the addition of calcium.The results showed that the particle size of sludge flocs increased and the particle size distribution tended to be narrow at the optimum dosage (168.5 mg/L).Calcium was effective in decreasing loosely bound extracellular polymeric substances (LB-EPS) in microbial flocs and soluble microbial products (SMP) in the supernatant at the dosage of 168.5 mg/L by strengthening the neutralization and bridging of EPS with flocs.Furthermore, the amount of CODS and CODC decreased in both the mixed liquor and the fouling cake layer on the membrane surface.In order to compare the filtration characteristics of cake layers from the MBRs with the two calcium dosages, the specific cake resistance and the compressibility coefficient were measured.The specific cake resistance from the MBR with optimum dosage (168.5 mg/L) was distinctly lower than that with low dosage (27 mg/L).The compressibility coefficient of the cake layers under different dosages were respectively attained as 0.65, 0.91.Scanning electron microscopy (SEM) and three-dimensional confocal scanning laser microscope analysis (CLSM) images were utilized to observe the gel layer directly.

  9. Simplified model for fouling of a pleated membrane filter

    Science.gov (United States)

    Sanaei, Pejman; Cummings, Linda

    2014-11-01

    Pleated filter cartridge are widely used to remove undesired impurities from a fluid. A filter membrane is sandwiched between porous support layers, then pleated and packed in to an annular cylindrical cartridge. Although this arrangement offers a high ratio of surface filtration area to volume, the filter performance (measured, e.g., by graph of total flux versus throughput for a given pressure drop), is not as good as a flat filter membrane. The reasons for this difference in performance are currently unclear, but likely factors include the additional resistance of the porous support layers upstream and downstream of the membrane, the pleat packing density (PPD) and possible damage to the membrane during the pleating process. To investigate this, we propose a simplified mathematical model of the filtration within a single pleat. We consider the fluid dynamics through the membrane and support layers, and propose a model by which the pores of the membrane become fouled (i) by particles smaller than the membrane pore size; and (ii) by particles larger than the pores.We present some simulations of our model, investigating how flow and fouling differ between not only flat and pleated membranes, but also for support layers of different permeability profiles. NSF DMS-1261596.

  10. Self-Replenishing Vascularized Fouling-Release Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Howell, C; Vu, TL; Lin, JJ; Kolle, S; Juthani, N; Watson, E; Weaver, JC; Alvarenga, J; Aizenberg, J

    2014-08-13

    Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectious bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella sauna, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.

  11. Low fouling polysulfone ultrafiltration membrane via click chemistry

    KAUST Repository

    Xie, Yihui

    2014-10-13

    Hydrophilic surfaces are known to be less prone to fouling. Ultrafiltration membranes are frequently prepared from rather hydrophobic polymers like polysulfone (PSU). Strategies to keep the good pore forming characteristics of PSU, but with improved hydrophilicity are proposed here. PSU functionalized with 1,2,3-triazole ring substituents containing OH groups was successfully synthesized through click chemistry reaction. The structures of the polymers were confirmed using NMR spectroscopy and Fourier transform infrared spectroscopy (FTIR). High thermal stability (>280°C) was observed by thermal gravimetric analysis. Elemental analysis showed the presence of nitrogen containing triazole group with different degrees of functionalization (23%, 49%, 56%, and 94%). The glass transition temperature shifted with the introduction of triazole pendant groups from 190°C (unmodified) to 171°C. Ultrafiltration membranes were prepared via phase inversion by immersion in different coagulation baths (NMP/water mixtures with volume ratios from 0/100 to 40/60). The morphologies of these membranes were studied by field emission scanning electron microscopy (FESEM). The optimized PSU bearing triazole functions membranes exhibited water permeability up to 187 L m-2 h-1 bar-1, which is 23 times higher than those prepared under the same conditions but with unmodified polysulfone (PSU; 8 L m-2 h-1 bar-1). Results of bovine serum albumin protein rejection test indicated that susceptibility to fouling decreased with the modification, due to the increased hydrophilicity, while keeping high protein rejection ratio (>99%).

  12. Nanomaterials for membrane fouling control: accomplishments and challenges.

    Science.gov (United States)

    Yang, Qian; Mi, Baoxia

    2013-11-01

    We report a review of recent research efforts on incorporating nanomaterials-including metal/metal oxide nanoparticles, carbon-based nanomaterials, and polymeric nanomaterials-into/onto membranes to improve membrane antifouling properties in biomedical or potentially medical-related applications. In general, nanomaterials can be incorporated into/onto a membrane by blending them into membrane fabricating materials or by attaching them to membrane surfaces via physical or chemical approaches. Overall, the fascinating, multifaceted properties (eg, high hydrophilicity, superparamagnetic properties, antibacterial properties, amenable functionality, strong hydration capability) of nanomaterials provide numerous novel strategies and unprecedented opportunities to fully mitigate membrane fouling. However, there are still challenges in achieving a broader adoption of nanomaterials in the membrane processes used for biomedical applications. Most of these challenges arise from the concerns over their long-term antifouling performance, hemocompatibility, and toxicity toward humans. Therefore, rigorous investigation is still needed before the adoption of some of these nanomaterials in biomedical applications, especially for those nanomaterials proposed to be used in the human body or in contact with living tissue/body fluids for a long period of time. Nevertheless, it is reasonable to predict that the service lifetime of membrane-based biomedical devices and implants will be prolonged significantly with the adoption of appropriate fouling control strategies.

  13. Investigation of the hydro-mechanical behaviour of fouled ballast

    Institute of Scientific and Technical Information of China (English)

    Yu-jun CUI; Trong Vinh DUONG; Anh Minh TANG; Jean-Claude DUPLA; Nicolas CALON; Alain ROBINET

    2013-01-01

    In this study,a fouled ballast taken from the site of Sénissiat,France,was investigated.For the hydraulic behaviour,a large-scale cell was developed allowing drainage and evaporation tests to be carried out with monitoring of both suction and volumetric water content at various positions of the sample.It was observed that the hydraulic conductivity of fouled ballast is decreasing with suction increase,as for common unsaturated soils.The effect of fines content was found to be negligible.For the mechanical behaviour,both monotonic and cyclic triaxial tests were carried out using a large-scale triaxial cell.Various water contents were considered.The results were interpreted in terms of shear strength and permanent axial strain.It appeared that the water content is an important factor to be accounted for since any increase of water content or degree of saturation significantly decreases the shear strength and increases the permanent strain.Constitutive modelling has been attempted based on the experimental results.The model in its current state is capable of describing the effects of stress level,cycle number and water content.

  14. The influence of hydrodynamic factors, membrane surface properties and channel geometries on membrane performance and fouling mechanisms

    Directory of Open Access Journals (Sweden)

    Pervov Alexey

    2016-01-01

    Full Text Available Modern theoretical understanding of colloidal and suspended matter membrane fouling mechanisms are presented and discussed. State-of-the-art simulation models of concentration polarization calculations for different channel conditions are described and influence of the fouling layers on the flux and rejection decrease are evaluated. Results of experimental investigations are presented that suggest a quantitative evaluation of fouling rates and membrane flux prognosis due to colloidal fouling with time. The influence of channel geometry on fouling is demonstrated and discussed. The main disadvantage of spiral wounded membrane modules which is attributed to the presence of a separation spacer mesh in the feed channel is discussed.

  15. Investigation of severe UF membrane fouling induced by three marine algal species

    KAUST Repository

    Merle, Tony

    2016-02-06

    Reducing membrane fouling caused by seawater algal bloom is a challenge for regions of the world where most of their freshwater is produced by seawater desalination. This study aims to compare ultrafiltration (UF) fouling potential of three ubiquitous marine algal species cultures (i.e., Skeletonena costatum-SKC, Tetraselmis sp.-TET, and Hymenomonas sp.-HYM) sampled at different phases of growth. Results showed that flux reduction and irreversible fouling were more severe during the decline phase as compared to the exponential phase, for all species. SKC and TET were responsible for substantial irreversible fouling but their impact was significantly lower than HYM. The development of a transparent gel layer surrounding the cell during the HYM growth and accumulating in water is certainly responsible for the more severe observed fouling. Chemical backwash with a standard chlorine solution did not recover any membrane permeability. For TET and HYM, the Hydraulically Irreversible Fouling Index (HIFI) was correlated to their biopolymer content but this correlation is specific for each species. Solution pre-filtration through a 1.2 μm membrane proved that cells and particulate algal organic matter (p-AOM) considerably contribute to fouling, especially for HYM for which the HIFI was reduced by a factor of 82.3.

  16. Assessment of anti-fouling strategies for membrane coupled with upflow anaerobic sludge blanket (MUASB) process.

    Science.gov (United States)

    Tran, Thao Minh; Ye, Yun; Chen, Vicki; Stuetz, Richard; Le-Clech, Pierre

    2013-01-01

    In this novel process, domestic wastewater was filtered by a hollow-fibre membrane coupled with an upflow anaerobic sludge blanket (MUASB) bioreactor. To improve the process sustainability and decrease energy costs, the membranes were operated under low fluxes with little, or no, shear. The efficiency of anti-fouling strategies, including relaxation, backwashing and supply of low aeration and stir rates, was assessed through detailed characterization of the fouling layers. Results indicated that backwashing was more efficient than relaxation, even when the systems were operated under the same flux productivity. In terms of shear supply, stir provided a better fouling limitation strategy compared to aeration, at similar shear stress values. Physical and chemical cleaning methods were applied to recover three fouling fractions (i.e. cake, residual and irreversible) for better characterization of the fouling layers. Under the sustainable operating conditions used in this study, most of the fouling was easily reversible by simple rinsing. In addition, permanent and irreversible fouling, resulting in the need for frequent chemical cleanings and potential membrane degradation, is limited once small shear stresses are applied. These outcomes are expected to form the basis for the future assessment of trade-off between operation, maintenance and replacement costs of membrane filtration processes used in wastewater treatment.

  17. Characterization of biofoulants illustrates different membrane fouling mechanisms for aerobic and anaerobic membrane bioreactors

    KAUST Repository

    Xiong, Yanghui

    2015-11-17

    This study compares the membrane fouling mechanisms of aerobic (AeMBR) and anaerobic membrane bioreactors (AnMBR) of the same reactor configuration at similar operating conditions. Although both the AeMBR and AnMBR achieved more than 90% COD removal efficiency, the fouling mechanisms were different. Molecular weight (MW) fingerprint profiles showed that a majority of fragments in anaerobic soluble microbial products (SMP) were retained by the membrane and some fragments were present in both SMP and in soluble extracellular polymeric substances (EPS), suggesting that the physical retention of SMP components contributed to the AnMBR membrane fouling. One of the dominant fragments was comprised of glycoliproprotein (size 630-640 kD) and correlated in abundance in AnMBR-EPS with the extent of anaerobic membrane fouling. In contrast, all detected AeMBR-SMP fragments permeated through the membrane. Aerobic SMP and soluble EPS also showed very different fingerprinting profiles. A large amount of adenosine triphosphate was present in the AeMBR-EPS, suggesting that microbial activity arising from certain bacterial populations, such as unclassified Comamonadaceae and unclassified Chitinophagaceae, may play a role in aerobic membrane fouling. This study underlines the differences in fouling mechanisms between AeMBR and AnMBR systems and can be applied to facilitate the development of appropriate fouling control strategies.

  18. Effect of fouling on removal of trace organic compounds by nanofiltration

    Directory of Open Access Journals (Sweden)

    S. Hajibabania

    2011-12-01

    Full Text Available The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l−1 were used to simulate fouling in nanofiltration under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.

  19. Irreversible membrane fouling abatement through pre-deposited layer of hierarchical porous carbons

    KAUST Repository

    Hamad, Juma

    2014-11-01

    In this work, dual-templated hierarchical porous carbons (HPCs), produced from a coupled ice-hard templating approach, are shown to be a highly effective solution to the commonly occurring problem of irreversible fouling of low-pressure membranes used for pre-treatment in wastewater reuse. For the first time, dual-templated HPCs, along with their respective counterparts - single-templated meso-porous carbon (MPCs) (without macropores) - are tested in terms of their fouling reduction capacity and ability to remove different effluent organic matter fractions present in wastewater and compared with a commercially available powdered activated carbon (PAC). The synthesized HPCs provided exceptional fouling abatement, a 4-fold higher fouling reduction as compared to the previously reported best performing commercial PAC and ~2.5-fold better fouling reduction than their respective mesoporous counterpart. Thus, it is shown that not only mesoporosity, but macroporosity is also necessary to achieve high fouling reduction, thus emphasizing the need for dual templating. In the case of HPCs, the pre-deposition technique is also found to outperform the traditional sorbent-feed mixing approach, mainly in terms of removal of fouling components. Based on their superior performance, a high permeability (ultra-low-pressure) membrane consisting of the synthesized HPC pre-deposited on a large pore size membrane support (0.45μm membrane), is shown to give excellent pre-treatment performance for wastewater reuse application. © 2014 Elsevier Ltd.

  20. Enhanced gypsum scaling by organic fouling layer on nanofiltration membrane: Characteristics and mechanisms.

    Science.gov (United States)

    Wang, Jiaxuan; Wang, Lei; Miao, Rui; Lv, Yongtao; Wang, Xudong; Meng, Xiaorong; Yang, Ruosong; Zhang, Xiaoting

    2016-03-15

    To investigate how the characteristics of pregenerated organic fouling layers on nanofiltration (NF) membranes influence the subsequent gypsum scaling behavior, filtration experiments with gypsum were carried out with organic-fouled poly(piperazineamide) NF membranes. Organic fouling layer on membrane was induced by bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA), respectively. The morphology and components of the scalants, the role of Ca(2+) adsorption on the organic fouling layer during gypsum crystallization, and the interaction forces of gypsum on the membrane surface were investigated. The results indicated that SA- and HA-fouled membranes had higher surface crystallization tendency along with more severe flux decline during gypsum scaling than BSA-fouled and virgin membranes because HA and SA macromolecules acted as nuclei for crystallization. Based on the analyses of Ca(2+) adsorption onto organic adlayers and adhesion forces, it was found that the flux decline rate and extent in the gypsum scaling experiment was positively related to the Ca(2+)-binding capacity of the organic matter. Although the dominant gypsum scaling mechanism was affected by coupling physicochemical effects, the controlling factors varied among foulants. Nevertheless, the carboxyl density of organic matter played an important role in determining surface crystallization on organic-fouled membrane.

  1. Effect of fouling on removal of trace organic compounds by nanofiltration

    Directory of Open Access Journals (Sweden)

    S. Hajibabania

    2011-09-01

    Full Text Available The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l−1 were used to simulate fouling in NF under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.

  2. Seawater ultrafiltration fouling control: Backwashing with demineralized water/SWRO permeate

    KAUST Repository

    Li, Sheng

    2012-09-01

    In this study, the effect of demineralized water backwashing on fouling control of seawater ultrafiltration was investigated. Seawater from Scheveningen beach in The Hague and a desalination plant of Evides Company at Zeeland in the Netherlands was used as feed water, while demineralized water and UF permeate were used as backwash water for a fouling control efficiency comparison under different fluxes and backwash durations. Furthermore, demineralized waters with 5 or 50 mmol/l NaCl were applied for backwashing as well, to check the influence of monovalent cations on UF fouling control. Additionally, SWRO permeate was used for backwashes in long-term experiments to check the possibility of it replacing demineralized water. Results show that seawater UF fouling control is substantially improved by demineralized water backwashing. However, due to the high salinity of seawater, more water was required to dilute the cation concentration and limit the dispersion effect near the membrane surface than was needed for surface water. A 2-min demineralized water backwash showed better fouling control efficiency than a 1-min backwash. Furthermore, the presence of monovalent cations in the backwash water deteriorated the fouling control efficiency of the backwash, indicating the existence of a charge screening effect. The demineralized water with 5 and 50 mmol/l NaCl both showed a similar fouling control efficiency which is better than the UF permeate backwash. The calcium ions in UF permeate probably deteriorates the fouling control efficiency by maintaining a Ca-bridging effect between the membranes and NOM. SWRO permeate backwashing successfully controls membrane fouling as well. © 2012 Elsevier B.V. All rights reserved.

  3. Flux dependency of particulate/colloidal fouling in seawater reverse osmosis systems

    KAUST Repository

    Salinas Rodríguez, S. G.

    2012-01-01

    Fouling is the main operational problem in seawater reverse osmosis systems (SWRO). Particulate fouling is traditionally measured through the silt density index (SDI) and through the modified fouling index (MFI). In recent years, ultrafiltration membranes were used successfully at constant flux-MFI-UF-to measure particulate/colloidal fouling potential and tested in sea water applications. Furthermore, constant flux operation allows predicting the rate of fouling in RO systems. The objectives of this study are: (1) to measure the flux effect in MFI-UF with different membranes (100, 30 and 10 kDa) for raw seawater and pre-treated water before reverse osmosis in three different locations; (2) to study the particulate and colloidal fouling potential of seawater in reverse osmosis systems; (3) to project the increase in pressure due to cake resistance in reverse osmosis systems. In this research, flat ultrafiltration membranes (100, 50, 30 and 10 kDa) are used in a con- stant flux filtration mode to test and compare real seawaters from various locations (North and Mediterranean Sea) and from various full scale facilities including different pre-treatments (i.e., ultrafiltration and coagulation + dual media filtration). The operated fluxes range from 350 down to values close to real RO operation, 15l(m2h)-1. After each filtration test, the MFI-UF is calculated to assess the particulate fouling potential. The obtained results showed that: (1) the particulate and colloidal fouling potential is directly proportional to the applied flux during filtration. This proportionality is related to the compression of the cake deposit occurring at high flux values; (2) the higher the flux, the higher the required pressure, the less porous the cake and therefore the higher the specific cake resistance; (3) particulate and colloidal fouling potential of seawater is site specific and is influenced by pre-treatment. © 2012 Desalination Publications. All rights reserved.

  4. Graft polymerization and plasma treatment of polymer membranes for fouling reduction: a review.

    Science.gov (United States)

    Kochkodan, Victor M; Sharma, Virender K

    2012-01-01

    This article presents a review of recent developments in surface modification of polymer membranes via graft polymerization and plasma treatment for reduction of fouling with organic compounds and microorganisms in pressure driven membrane processes. The factors affecting membrane fouling, such as membrane hydrophilicity, charge and surface roughness are discussed. The recent studies in which the reduction of organic fouling and biofouling by the modification of the membrane surface via ultraviolet/redox initiated surface grafting of hydrophilic polymers and low temperature plasma treatment are reviewed.

  5. Coke fouling process on the oil refining; Processo de incrustacao por coque no refino do petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Bombardelli, Clovis; Fiorentin, Leila D.; Negrao, Cezar O.R.; Franco, Admilson T. [Centro Federal de Educacao Tecnologica do Parana (CEFET-PR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica e de Materiais (PPGEM)

    2004-07-01

    The heavy crude fraction processing is performed under very high vacuum to minimize thermal cracking which cause coke deposition and damage the equipment. The current tendency is to process heavier oil leading to higher process temperatures and consequently to greater fouling. This situation demands better knowledge fouling process by carbonization. This problem is pronounced in the residual gasoil region of a vacuum distillation unit because it obstructs the recirculation circuits and the spray system with serious environmental and economics implications. This paper review the main correlated published work related to coke generation and fouling and presents a discussion about the works. (author)

  6. Fouling Bryozoa from some Alexandria harbours, EGYPT. (I Erect species

    Directory of Open Access Journals (Sweden)

    KH.M. ABDEL-SALAM

    2012-12-01

    Full Text Available The fouling erect Bryozoa settled on polystyrene test panels immersed half a meter deep in the water of Abu Qir Harbour, the Eastern Harbour and El-Dekheila Harbour were studied. The present study yields 5 species of erect bryozoa. These areAmathia pruvoti, Zoobotryon verticillatum, Bowerbankia gracilis,Bugula neritina and Bugula stolonifera. The first three ones pertain to 3 genera of the family Vesiculariidae belonging to suborder the Stolonifera; while the other two species affiliate to the genus Bugula belonging to the family Bugulidae of suborder Anasca. The present record of Amathia pruvoti is the first from the Egyptian Mediterranean waters. A re-description, supplied with full structural illustrations of the recorded species is given. Moreover, the temporal and spatial distributions of the species recorded are encountered.

  7. Fuel efficiency and fouling control coatings in maritime transport

    DEFF Research Database (Denmark)

    Lindholdt, Asger

    First, this thesis concerns the drag performance of fouling control coatings (FCCs) used to protect hulls on ships against biofouling and, therefore, minimize any drag therefrom. A systematic overview of the literature and description of the experimental methods used to quantify the drag of FCCs...... currently used consists of measuring drag when coatings are newly applied and after static exposure. It was found that the main limitation of this method primarily arises due to incorrect exposure conditions, when compared to larger commercial ships that mainly are moving with few and shorter idle periods...... with a radius of 11.45 cm. The drag performances in the newly applied coating condition and after one month of static immersion in natural seawater were measured using a friction disk machine (FDM). The four best performing coatings were re-examined for their drag performance after an additional 2.5 months...

  8. Poly(dimethyl siloxane) (PDMS) network blends of amphiphilic acrylic copolymers with poly(ethylene glycol)-fluoroalkyl side chains for fouling-release coatings. II. Laboratory assays and field immersion trials.

    Science.gov (United States)

    Martinelli, Elisa; Sarvothaman, Mahesh K; Galli, Giancarlo; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Conlan, Sheelagh L; Clare, Anthony S; Sugiharto, Albert B; Davies, Cait; Williams, David

    2012-01-01

    Amphiphilic copolymers containing different amounts of poly(ethylene glycol)-fluoroalkyl acrylate and polysiloxane methacrylate units were blended with a poly(dimethyl siloxane) (PDMS) matrix in different proportions to investigate the effect of both copolymer composition and loading on the biological performance of the coatings. Laboratory bioassays revealed optimal compositions for the release of sporelings of Ulva linza, and the settlement of cypris larvae of Balanus amphitrite. The best-performing coatings were subjected to field immersion tests. Experimental coatings containing copolymer showed significantly reduced levels of hard fouling compared to the control coatings (PDMS without copolymer), their performance being equivalent to a coating based on Intersleek 700™. XPS analysis showed that only small amounts of fluorine at the coating surface were sufficient for good antifouling/fouling-release properties. AFM analyses of coatings under immersion showed that the presence of a regular surface structure with nanosized domains correlated with biological performance.

  9. An anti-fouling aptasensor for detection of thrombin by dual polarization interferometry.

    Science.gov (United States)

    Zheng, Yu; Hu, Tao; Chen, Chuanxia; Yang, Fan; Yang, Xiurong

    2015-04-04

    An anti-fouling surface was designed to effectively resist nonspecific protein adsorption using dual polarization interferometry, based on which the aptasensor for detection of thrombin was fabricated according to the specific interaction between thrombin and its 15-mer aptamer.

  10. Combined organic-inorganic fouling of forward osmosis hollow fiber membranes.

    Science.gov (United States)

    Arkhangelsky, Elizabeth; Wicaksana, Filicia; Tang, Chuyang; Al-Rabiah, Abdulrahman A; Al-Zahrani, Saeed M; Wang, Rong

    2012-12-01

    This research focused on combined organic-inorganic fouling and cleaning studies of forward osmosis (FO) membranes. Various organic/inorganic model foulants such as sodium alginate, bovine serum albumin (BSA) and silica nanoparticles were applied to polyamide-polyethersulfone FO hollow fiber membranes fabricated in our laboratory. In order to understand all possible interactions, experiments were performed with a single foulant as well as combinations of foulants. Experimental results suggested that the degree of FO membrane fouling could be promoted by synergistic effect of organic foulants, the presence of divalent cations, low cross-flow velocity and high permeation drag force. The water flux of fouled FO hollow fibers could be fully restored by simple physical cleaning. It was also found that hydrodynamic regime played an important role in combined organic-inorganic fouling of FO membranes.

  11. Flux Recovery of a Forward Osmosis Membrane After a Fouling Process

    Science.gov (United States)

    Romero-Mangado, Jaione; Parodi, Jurek; Gamboa-Vazquez, Sonia; Stefanson, Ofir; Diaz-Cartagena, Diana C.; Flynn, Michael

    2016-01-01

    Wastewater treatment through forward osmosis (FO) membranes is a process that has been evaluated in the past years as an innovative technology for the Next Generation Life Support Systems. FO technologies are cost effective, and require very low energy consumption, but are subject to membrane fouling. Membrane fouling occurs when unwanted materials accumulate on the active side of the membrane during the wastewater treatment process, which leads to a decrease in membrane flux rate. The aim of this study is to identify the materials that cause flux rate reduction due to membrane fouling, as well as to evaluate the flux rate recovery after membrane treatment using commercially available antifoulants. Fourier Transform Infrared (FTIR) spectrometry results identified possible compounds that cause membrane fouling and FO testing results demonstrated flux rate recovery after membrane treatment using antifoulants.

  12. Development of a Comprehensive Fouling Model for a Rotating Membrane Bioreactor System Treating Wastewater

    Directory of Open Access Journals (Sweden)

    Parneet Paul

    2015-01-01

    Full Text Available Membrane bioreactors (MBRs are now main stream wastewater treatment technologies. In recent times, novel pressure driven rotating membrane disc modules have been specially developed that induce high shear on the membrane surface, thereby reducing fouling. Previous research has produced dead-end filtration fouling model which combines all three classical mechanisms that was later used by another researcher as a starting point for a greatly refined model of a cross flow side-stream MBR that incorporated both hydrodynamics and soluble microbial products’ (SMP effects. In this study, a comprehensive fouling model was created based on this earlier work that incorporated all three classical fouling mechanisms for a rotating MBR system. It was tested and validated for best fit using appropriate data sets. The initial model fit appeared good for all simulations, although it still needs to be calibrated using further appropriate data sets.

  13. Field testing of a probe to measure fouling in an industrial flue gas stream

    Energy Technology Data Exchange (ETDEWEB)

    Sohal, M.S.

    1990-11-01

    The US Department of Energy, Office of Industrial Technology sponsors work in the area of measuring and mitigating fouling in heat exchangers. This report describes the design and fabrication of a gas-side fouling measuring device, and its testing in an industrial environment. The report gives details of the probe fabrication, material used, controllers, other instrumentation required for various measurements, and computer system needed for recording the data. The calibration constants for measuring the heat flux with the heat fluxmeter were determined. The report also describes the field test location, the tests performed, the data collected, and the data analysis. The conclusions of the tests performed were summarized. Although fouling deposits on the probe were minimal, the tests proved that the probe is capable of measuring the fouling in a harsh industrial environment. 17 refs., 19 figs., 5 tabs.

  14. Use of Ultrasonic Sensors for Characterization of Membrane Fouling and Cleaning

    Directory of Open Access Journals (Sweden)

    Elmira Kujundzic, Ph.D.

    2008-06-01

    Full Text Available The modern challenges for membrane separations in a wide range of processes require more sophisticated approaches for the detection and remediation of fouling, i.e., the association of solutes, particulate matter, and colloids on and/or within a membrane. Most commonly, fouling is assessed from inferred measurements of permeation rate and/or permeate quality. The use of acoustic techniques for direct observations of membrane fouling was introduced over 10 years ago. We summarize here, recent developments in ultrasonic reflectometry that use both time-domain and frequency-domain spectra for noninvasive, real-time assessments of fouling in a variety of module configurations and geometries. In addition, we describe recent developments and applications of scanning acoustic microscopy (SAM for post-mortem characterization of membranes with particular emphasis on biofouling.

  15. Fouling diatom community with reference to substratum variability in tropical marine environment

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Desai, D.V.; Khandeparker, L.; Anil, A.C.; Wagh, A.B.

    Diatoms are the earliest autotrophic colonizers and are responsible for the major input of energy in the form of reduced carbon to the surfce. However, information regarding the population structure of diatoms in theearly phases of fouling is very...

  16. Observation on fouling organisms collected from Indian naval ships at Bombay

    Directory of Open Access Journals (Sweden)

    V. Gopalakrishnan

    1959-01-01

    Full Text Available Fouling organisms collected from Indian Naval Ships dry-docked at Bombay during a period of two years (July 1956-June 1958 were studied in detail. Forty six of the forms collected have been identified. The most important groups of ship-fouling Organisms in Bombay waters are Barnacles, Hydroids, Polyzoans and Tube-worms. Eleven different Fouling Communities have been found to dominate the settlements on the hulls at different occasions. Definite zonations that could be observed were restriction of green algae to the boot-top area and mussels and oysters to the pipes and gratings. An attempt has been made to find the sequence of settlement of the different major fouling groups. Some general remarks on the observations have also been included.

  17. Design of shell-and-tube heat exchangers when the fouling depends on local temperature and velocity

    Energy Technology Data Exchange (ETDEWEB)

    Butterworth, D. [HTFS, Hyprotech, Didcot (United Kingdom)

    2002-07-01

    Shell-and-tube heat exchangers are normally designed on the basis of a uniform and constant fouling resistance that is specified in advance by the exchanger user. The design process is then one of determining the best exchanger that will achieve the thermal duty within the specified pressure drop constraints. It has been shown in previous papers [Designing shell-and-tube heat exchangers with velocity-dependant fouling, 34th US national Heat Transfer Conference, 20-22 August 2000, Pittsburg, PA; Designing shell-and-tube heat exchangers with velocity-dependant fouling, 2nd Int. Conf. on Petroleum and Gas Phase Behavior and Fouling, 27-31 August 2000, Copenhagen] that this approach can be extended to the design of exchangers where the design fouling resistance depends on velocity. The current paper briefly reviews the main findings of the previous papers and goes on to treat the case where the fouling depends also on the local temperatures. The Ebert-Panchal [Analysis of Exxon crude-oil, slip-stream coking data, Engineering Foundation Conference on Fouling Mitigation of Heat Exchangers, 18-23 June 1995, California] form of fouling rate equation is used to evaluate this fouling dependence. When allowing for temperature effects, it becomes difficult to divorce the design from the way the exchanger will be operated up to the point when the design fouling is achieved. However, rational ways of separating the design from the operation are proposed. (author)

  18. Understanding the fouling of algogenic organic matter in microfiltration using membrane-foulant interaction energy analysis: effects of organic hydrophobicity.

    Science.gov (United States)

    Huang, Weiwei; Chu, Huaqiang; Dong, Bingzhi

    2014-10-01

    Fouling caused by algogenic organic matter (AOM) in membrane filtration is a critical problem in algae-rich waters, and understanding fouling mechanisms, particularly by identifying the predominant membrane foulants, could have significant effects on algal fouling prediction and pretreatment. In this work, the fouling behavior of Aphanizomenon flos-aquae (APF)- and Anabaena flos-aquae (ANF)-AOM fractions was analyzed using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. The results show that the interfacial energy of membranes and foulants could be used for AOM membrane fouling analysis. The attractive energy was highest between the membrane and the neutral hydrophilic fractions (N-HPI) on clean membrane surfaces, followed by the energy associated with the hydrophobic fractions (HPO) and the transphilic fractions (TPI) in both of the AOMs; on the other hand, the negatively charged hydrophilic organics (C-HPI) in the APF-AOM suffered from repulsive interactions when nearing the membrane surface, which was consistent with their initial filtration flux. After the formation of an initial fouling layer on the membrane surface, membrane fouling was controlled mainly by the cohesion free energy between the approaching foulants and the foulants on the fouled membranes. In addition, it was observed that the interfacial energy between foulants was the dominant factor controlling membrane fouling in AOM filtration. Finally, the interfacial energies between the N-HPI fractions had the greatest effect on both APF-AOM and ANF-AOM membrane fouling.

  19. [Impacts of filamentous bulking on treatment effect and fouling characteristics of nonwoven bioreactor].

    Science.gov (United States)

    Shi, Kuan; Xue, Gang; Gao, Pin; Wu, Fan

    2014-06-01

    Sludge flocs morphology and effluent qualities of nonwoven bioreactor during filamentous bulking and normal sludge status were compared. Flux variations, analysis of filtration resistances and extracellular polymer substances (EPS) contents during filamentous bulking and normal sludge status were studied. The results showed that the average particle size of bulking sludge flocs and normal sludge flocs was 448.6 microm and 234.8 microm, respectively. During the bulking sludge status, the average COD and NH4(+) -N removal rate and effluent turbidity were 90.1%, 93.1% and 1.33 NTU, respectively, compared with 91.4% , 97.0% and 0.99 NTU during the normal sludge status. Filamentous bulking had little impact on COD removal, while it inhibited NH4(+) -N removal to a certain extent and had slight impact on effluent turbidity. Average membrane flux decay rates during the bulking sludge status and the normal sludge status were 3.29 L x (m2 x h2)(-1) and 4.87 L x (m2 x h2)(-1), respectively, and the fouling during bulking sludge status was slighter. Reversible fouling was the main fouling when sludge was bulking while irreversible fouling was the main fouling when the sludge was in normal status. The prior occurrence of reversible fouling could reduce irreversible fouling therefore slow down the flux decline. Soluble microbial products (SMP) contents in normal sludge mixed liquid and bulking sludge mixed liquid were 21.369 mg x L(-1) and 10.182 mg x L(-1), respectively, protein/polysaccharide (P/C) was 0.370 and 0.497, respectively, SMP gross was related to fouling resistance and P/C was associated with reversible fouling proportion. The relation between loosely bound EPS in mixed liquid sludge and membrane fouling was similar to SMP. Sludge with more EPS could accumulate on membrane more easily, and the EPS that accumulated on membrane was mainly protein. EPS gross in mixed liquid sludge, EPS in membrane surface sludge and their P/C all had positive correlations to

  20. Application of Several Techniques for Prohibiting Fouling in Li-Recovery Pilot Plant

    Science.gov (United States)

    Yoon, H.; Kim, D.; Gong, M.; Kim, B.; Chung, K.

    2010-12-01

    The problem of marine organisms adhering to any surfaces exposed in seawater is as old as time. Marine fouling is a major problem in the materials used in seawater worldwide. Marine coatings contain elements such as copper and triorganotin compounds were often used as an effective compound for control the fouling problem, but application of such coatings containing triorganotin compounds was prohibited and the former are considered undesirable because of its toxicity and accumulative in non-target organisms. Monitoring and field studies regarding fouling problems during operation of Li-recovery pilot plant which is designed by the Korea Institute of Geoscience & Mineral Resources (KIGAM) were major concern of this study. Fouling could be the most troublesome tasks during the development of a large scale pilot production test for achieving a high performance adsorbent for seawater dissolved Li recovery. Chemical and microbiological characteristics of the fouling biofilms developed on various surfaces in contact with the seawater were made. The microbial compositions of the biofilm consortia formed on the reservoir polymer surfaces were also tested for. The quantities of the diverse microorganisms in the biofilm samples developed on the prohibiting polymer reservoir surface were larger when there was no concern about materials for special selection for fouling. The experimental results offered new specific information, concerning the problems in the application of new material as well as surface coating such as anti-fouling coatings. They showed the important role microbial activity in fouling and corrosion of the surfaces in contact with the any seawater. Acknowledgements: This research was supported by a grant from the Development of Technology for Extraction of Resources Dissolved in Sea Water Program funded by Ministry of Land Transport and Maritime Affairs in Korean Government (2010).

  1. Influence of twisted tape turbulence promoter on fouling reduction in microfiltration of milk proteins

    Directory of Open Access Journals (Sweden)

    Popović Svetlana S.

    2011-01-01

    Full Text Available Membrane filtration has become one of the major technologies in the food industry. It is widely applied in the dairy industry, and it is mostly used for the concentration and fractionation of milk proteins and for the whey processing. Of all pressure driven membrane processes, ultrafiltration is the most widely used. The major disadvantage of pressure driven membrane processes is severe fouling of membrane during filtration particularly when the fluids containing proteins are processed. Fouling with proteins is complex phenomenon because it occurs at the membrane surface as well as in the pores of membrane, and depends on the operating conditions and on the interactions of proteins and membrane material. In order to reduce fouling of the membrane different techniques have been developed, and one of them relies on the changing of the hydrodynamic conditions in the membrane or module. In this study, influence of twisted tape turbulence promoters on the fouling reduction in cross-flow microfiltration of skim milk was investigated. Twisted tapes with tree characteristic ratios of helix element length to the tape diameter (aspect ratio were studied. It was shown that twisted tapes with different aspect ratios reduce fouling of membrane by a factor of three or more. The presence of twisted tape induces changes in the flow patterns from straight to helicoidally thus producing turbulence flow at the lower cross-flow rates. Turbulence intensification prevents accumulation of proteins at membrane surface enabling reduction in reversible fouling what results in the reduction of overall membrane fouling. The best performance was achieved using a twisted tape with the lowest aspect ratio of 1.0. This promoter reduces fouling seven times at low transmembrane pressure and low cross-flow velocity. The twisted tape with aspect ratio 1.0 induces the most intensive turbulence, the longest helicoidal flow path, and appearance of vortices near the membrane surfaces

  2. The role of NOM fouling for the retention of estradiol and ibuprofen during ultrafiltration

    OpenAIRE

    Jermann, Doris; Pronk, Wouter; Boller, Markus; Schaefer, Andrea I.

    2009-01-01

    The impact of membrane fouling by natural organic matter (NOM) on the behavior of micropollutants during ultrafiltration (UF) was investigated. Batch experiments with radioactively labeled estradiol and ibuprofen in the presence of NOM model compounds (alginate, Nordic aquatic and Aldrich humic acid) were performed using a hydrophilic and a hydrophobic membrane. The results indicate that the impact of the NOM fractions studied on micropollutant retention correlated with the fouling mechanism ...

  3. Hydrophilic, bactericidal nanoheater-enabled reverse osmosis membranes to improve fouling resistance.

    Science.gov (United States)

    Ray, Jessica R; Tadepalli, Sirimuvva; Nergiz, Saide Z; Liu, Keng-Ku; You, Le; Tang, Yinjie; Singamaneni, Srikanth; Jun, Young-Shin

    2015-06-01

    Polyamide (PA) semipermeable membranes typically used for reverse osmosis water treatment processes are prone to fouling, which reduces the amount and quality of water produced. By synergistically coupling the photothermal and bactericidal properties of graphene oxide (GO) nanosheets, gold nanostars (AuNS), and hydrophilic polyethylene glycol (PEG) on PA reverse osmosis membrane surfaces, we have dramatically improved fouling resistance of these membranes. Batch fouling experiments from three classes of fouling are presented: mineral scaling (CaCO3 and CaSO4), organic fouling (humic acid), and biofouling (Escherichia coli). Systematic analyses and a variety of complementary techniques were used to elucidate fouling resistance mechanisms from each layer of modification on the membrane surface. Both mineral scaling and organic fouling were significantly reduced in PA-GO-AuNS-PEG membranes compared to other membranes. The PA-GO-AuNS-PEG membrane was also effective in killing all near-surface bacteria compared to PA membranes. In the PA-GO-AuNS-PEG membrane, the GO nanosheets act as templates for in situ AuNS growth, which then facilitated localized heating upon irradiation by an 808 nm laser inactivating bacteria on the membrane surface. Furthermore, AuNS in the membrane assisted PEG in preventing mineral scaling on the membrane surface. In flow-through flux and foulant rejection tests, PA-GO-AuNS-PEG membranes performed better than PA membranes in the presence of CaSO4 and humic acid model foulants. Therefore, the newly suggested membrane surface modifications will not only reduce fouling from RO feeds, but can improve overall membrane performance. Our innovative membrane design reported in this study can significantly extend the lifetime and water treatment efficacy of reverse osmosis membranes to alleviate escalating global water shortage from rising energy demands.

  4. Effect of IX dosing on polypropylene and PVDF membrane fouling control

    KAUST Repository

    Myat, Darli Theint

    2013-07-01

    The performance of ion exchange (IX) resin for organics removal from wastewater was assessed using advanced characterisation techniques for varying doses of IX. Organic characterisation using liquid chromatography with a photodiode array (PDA) and fluorescence spectroscopy (Method A), and UV254, organic carbon and organic nitrogen detectors (Method B), was undertaken on wastewater before and after magnetic IX treatment. Results showed partial removal of the biopolymer fraction at high IX doses. With increasing concentration of IX, evidence for nitrogen-containing compounds such as proteins and amino acids disappeared from the LC-OND chromatogram, complementary to the fluorescence response. A greater fluorescence response of tryptophan-like proteins (278nm/343nm) for low IX concentrations was consistent with aggregation of tryptophan-like compounds into larger aggregates, either by self-aggregation or with polysaccharides. Recycling of IX resin through multiple adsorption steps without regeneration maintained the high level of humics removal but there was no continued removal of biopolymer. Subsequent membrane filtration of the IX treated waters resulted in complex fouling trends. Filtration tests with either polypropylene (PP) or polyvinylidene fluoride (PVDF) membranes showed higher rates of initial fouling following treatment with high IX doses (10mL/L) compared to filtration of untreated water, while treatment with lower IX doses resulted in decreased fouling rates relative to the untreated water. However, at longer filtration times the rate of fouling of IX treated waters was lower than untreated water and the relative fouling rates corresponded to the amount of biopolymer material in the feed. It was proposed that the mode of fouling changed from pore constriction during the initial filtration period to filter cake build up at longer filtration times. The organic composition strongly influenced the rate of fouling during the initial filtration period due to

  5. Use of Fillers, Pigments and Additives in Fouling-Release Coatings: a Literature Review

    OpenAIRE

    Tamaev, Nail; Kiil, Søren; Noguer, Albert Camós; Olsen, Stefan Møller

    2015-01-01

    Polydimethylsiloxane (PDMS)-based fouling-release coatings represent a non-toxic alternative in the area of marine protection. Many researches and testing procedures are dedicated to the challenge of exploring of effective, reliable and high-performance constituents of the coatings ‒ fillers, pigments and additives ‒ in order to achieve the desired and long-lasting fouling-release properties.Primarily, coating formulations are prepared on the basis of PDMS with inorganic fillers such as fumed...

  6. Relating reverse and forward solute diffusion to membrane fouling in osmotically driven membrane processes.

    Science.gov (United States)

    She, Qianhong; Jin, Xue; Li, Qinghua; Tang, Chuyang Y

    2012-05-01

    Osmotically driven membrane processes, such as forward osmosis (FO) and pressure retarded osmosis (PRO), are attracting increasing interest in research and applications in environment and energy related fields. In this study, we systematically investigated the alginate fouling on an osmotic membrane during FO operation using four types of draw solutions (NaCl, MgCl(2), CaCl(2) and Ca(NO(3))(2)) to elucidate the relationships between reverse (from draw solution to feed solution) and forward (from feed solution to draw solution) solute diffusion, and membrane fouling. At the same water flux level (achieved by adjusting the draw solution concentration), the greatest reverse solute diffusion rate was observed for NaCl draw solution, followed by Ca(NO(3))(2) draw solution, and then CaCl(2) draw solution and MgCl(2) draw solution, the order of which was consistent with that of their solute permeability coefficients. Moreover, the reverse solute diffusion of draw solute (especially divalent cation) can change the feed solution chemistry and thus enhance membrane fouling by alginate, the extent of which is related to the rate of the reverse draw solute diffusion and its ability to interact with the foulant. The extent of fouling for the four types of draw solution followed an order of Ca(NO(3))(2) > CaCl(2) > MgCl(2) > NaCl. On the other hand, the rate of forward diffusion of feed solute (e.g., Na(+)) was in turn promoted under severe membrane fouling in active layer facing draw solution orientation, which may be attributed to the fouling enhanced concentration polarization (pore clogging enhanced ICP and cake enhanced concentration polarization). The enhanced concentration polarization can lead to additional water flux reduction and is an important mechanism governing the water flux behavior during FO membrane fouling. Findings have significant implications for the draw solution selection and membrane fouling control in osmotically driven membrane processes.

  7. Fouling and Cleaning of Membrane Filtration Systems in the Dairy Industry

    DEFF Research Database (Denmark)

    Berg, Thilo Heinz Alexander

    of fouling residues were investigated. Both online and offline methods were found unsuitable to follow the whole process of fouling and cleaning as the concentration of protein residues on the membrane surface sooner or later reaches a level below the limit of detection of the respective methods. The main...... of membranes in bench scale. The results obtained in this thesis and the given literature overview is expected to help optimizing future membrane cleaning in the dairy industry....

  8. Anti-fouling properties of Fab' fragments immobilized on silane-based adlayers

    Science.gov (United States)

    Crivianu-Gaita, Victor; Romaschin, Alexander; Thompson, Michael

    2015-12-01

    Biosensors require surfaces that are highly specific towards the target analyte and that are minimally fouling. However, surface tuning to minimize fouling is a difficult task. The last decade has seen an increase in the use of immobilized antigen-binding antibody fragments (Fab') in biosensors. One Fab' linker compound S-(11-trichlorosilyl-undecanyl)-benzothiosulfonate (TUBTS) and three spacers were used to create the silane-based adlayers. The ultra-high frequency electromagnetic piezoelectric acoustic sensor (EMPAS) was used to gauge the fouling properties of the various surfaces using bovine serum albumin (BSA), goat IgG, and mouse serum. X-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM) were employed to characterize the surfaces. It was discovered that immobilized oriented Fab' fragments reduced the fouling levels of surfaces up to 80% compared to the surfaces without fragments. An explanation for this phenomenon is that the antibody fragments increase the hydration of the surfaces and aid in the formation of an anti-fouling water barrier. The anti-fouling effect of the Fab' fragments is at its maximum when there is an even distribution of fragments across the surfaces. Finally, using Fab'-covered surfaces, a cancer biomarker was detected from serum, showing the applicability of this work to the field of biodetection.

  9. Anti-fouling effect of bentonite suspension in ultrafiltration of oil/water emulsion.

    Science.gov (United States)

    Panpanit, S; Visvanathan, C; Muttamara, S

    2002-03-01

    The effect on membrane fouling resistance during ultrafilration of oil/water emulsion with the presence of bentonite suspension is experimentally evaluated. The fouling resistance was analyzed as a function of different membrane types and bentonite concentration. The total membrane fouling was categorized into reversible and irreversible, by adopting an appropriate chemical cleaning technique. The results revealed a 40% flux augmentation with the increase of bentonite concentration up to an optimum value of 300 mg l(-1) for cellulose acetate membrane. Further increase of bentonite concentration led to particle deposition on the membrane surface and reduced the flux. The polysulfone membrane did not show a similar flux improvement. This could be due to its high hydrophobicity. The absorption of oil/water emulsion on bentonite increased TOC removal rate from 65% to 80%, and this effect was the major cause of reduction in gel layer formation on the membrane surface. The extent of irreversible fouling of the hydrophilic cellulose acetate membrane was much smaller than that of the polysulfone membrane. These experiments demonstrated that, presence of bentonite could induce transformation of irreversible fouling caused by oil emulsion to reversible fouling, which could be periodically chemically cleaned.

  10. [Membrane fouling by secondary effluent of urban sewage and the membrane properties].

    Science.gov (United States)

    Meng, Xiao-rong; Zhang, Hai-zhen; Wang, Lei; Wang, Xu-dong; Zhao, Liang

    2013-05-01

    The fouling behavior of UF membranes by secondary effluent of municipal wastewater was investigated using both original PVDF membranes and PVA, PVP and PMMA modified PVDF membranes. The results showed that the structure parameters of UF membranes were optimized by blending; PVP and PVA could effectively improve the hydrophilicity and permeate flux of the membranes. The hydrophilicity and structure properties of UF membrane had stronger effect on the anti-fouling properties. Pore plugging resistance was the main reason for the unrecoverable fouling. For UF membranes with stronger hydrophilicity, there was some flux reduction in the initial filtration, which was attributed to the formation of concentration polarization layer. However, this layer can be easily removed and the irreversible fouling index (r(ir)) was 0, thus guaranteeing the membrane a better anti-fouling property. The dense membrane surface could prevent low-molecular-weight pollutants from entering the internal pores of the membrane. For UF membrane with fully developed macropores in the cross-section and loose spongy layer structure, pollutants deposition to membrane internal pores, which would cause membrane pore plugging, could be effectively inhibited. In contrast, for membranes with porous surface and not fully developed macropores in the cross-section, pore plugging was more prone to occur. As a result, flux declined seriously and was difficult to be recovered by physical cleaning, which gave rise to the irreversible fouling.

  11. Effect of components in activated sludge liquor on membrane fouling in a submerged membrane bioreactor

    Institute of Scientific and Technical Information of China (English)

    YU Shui-li; ZHAO Fang-bo; ZHANG Xiao-hui; JING Guo-lin; ZHEN Xiang-hua

    2006-01-01

    By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of flocs, soluble microorganism products (SMPs) and metal ions in activated sludge liquor on membrane fouling were investigated. The results showed that foulants absorbed each other and formed a fouling layer as a "second membrane" influencing the permeability of the membrane.The "gel layer" caused by SMPs and "cake layer" by flocs showed great differences in morphology by analysis of scanning electron microscope and atomic force microscope. The "gel layer" was more compact and of poor permeability. When the membrane flux was MPa/h). SMPs played very important roles on membrane fouling. In the bu1king sludge, with SMPs increasing, the rate of membrane fouling (0.0132 MPa/h) was faster. While after flocculation of the SMPs, the rate of fouling decreased to 0.0034 MPa/h. Flocs could keep holes in their overlaps. They could alleviate membrane fouling by preventing the SMPs directly attaching on membrane surface.

  12. Colloidal Fouling of Nanofiltration Membranes: Development of a Standard Operating Procedure

    Science.gov (United States)

    Al Mamun, Md Abdullaha; Bhattacharjee, Subir; Pernitsky, David; Sadrzadeh, Mohtada

    2017-01-01

    Fouling of nanofiltration (NF) membranes is the most significant obstacle to the development of a sustainable and energy-efficient NF process. Colloidal fouling and performance decline in NF processes is complex due to the combination of cake formation and salt concentration polarization effects, which are influenced by the properties of the colloids and the membrane, the operating conditions of the test, and the solution chemistry. Although numerous studies have been conducted to investigate the influence of these parameters on the performance of the NF process, the importance of membrane preconditioning (e.g., compaction and equilibrating with salt water), as well as the determination of key parameters (e.g., critical flux and trans-membrane osmotic pressure) before the fouling experiment have not been reported in detail. The aim of this paper is to present a standard experimental and data analysis protocol for NF colloidal fouling experiments. The developed methodology covers preparation and characterization of water samples and colloidal particles, pre-test membrane compaction and critical flux determination, measurement of experimental data during the fouling test, and the analysis of that data to determine the relative importance of various fouling mechanisms. The standard protocol is illustrated with data from a series of flat sheet, bench-scale experiments. PMID:28106775

  13. Effect of membrane bioreactor solids retention time on reverse osmosis membrane fouling for wastewater reuse.

    Science.gov (United States)

    Farias, Elizabeth L; Howe, Kerry J; Thomson, Bruce M

    2014-02-01

    The effect of the solids retention time (SRT) in a membrane bioreactor (MBR) on the fouling of the membranes in a subsequent reverse osmosis (RO) process used for wastewater reuse was studied experimentally using a pilot-scale treatment system. The MBR-RO pilot system was fed effluent from the primary clarifiers at a large municipal wastewater treatment plant. The SRT in the MBRs was adjusted to approximately 2, 10, and 20 days in three experiments. The normalized specific flux through the MBR and RO membranes was evaluated along with inorganic and organic constituents in the influent and effluent of each process. Increasing the SRT in the MBR led to an increase in the removal of bulk DOC, protein, and carbohydrates, as has been observed in previous studies. Increasing the SRT led to a decrease in the fouling of the MBR membranes, which is consistent with previous studies. However, the opposite trend was observed for fouling of the RO membranes; increasing the SRT of the MBR resulted in increased fouling of the RO membranes. These results indicate that the constituents that foul MBR membranes are not the same as those that foul RO membranes; to be an RO membrane foulant in a MBR-RO system, the constituents must first pass through the MBR membranes without being retained. Thus, an intermediate value of SRT may be best choice of operating conditions in an MBR when the MBR is followed by RO for wastewater reuse.

  14. Static adsorptive fouling of extracellular polymeric substances with different membrane materials.

    Science.gov (United States)

    Su, Xinying; Tian, Yu; Zuo, Wei; Zhang, Jun; Li, Hui; Pan, Xiaoyue

    2014-03-01

    Adsorptive fouling of microbial extracellular polymeric substances (EPS) greatly influences the fouling behavior and membrane characteristics in a membrane bioreactor (MBR). In this study, adsorptive fouling of the EPS on different membrane materials was compared and adsorptive mechanism between membranes and EPS was investigated by thermodynamic analysis. The results suggested that both the absolute and relative changes of hydraulic resistances should be considered to evaluate fouling of membranes with different materials, and Sips isotherm was the most suitable model to describe the EPS carbohydrate and protein adsorptions on membranes. Thermodynamic analysis showed that both EPS carbohydrate and protein adsorptions were spontaneous (ΔrG(θ)  0), and entropy driven (ΔrS(θ) > 0). Decreasing ΔrG(θ) values with temperature suggested that EPS adsorptive fouling can be limited by reducing temperature. In addition, physisorption processes and hydrogen bonding interactions between EPS and membranes might play a relatively major role in the adsorption mechanism of EPS on the membrane surface. Atomic force microscopy (AFM) and contact angle analysis confirmed that the adsorptive fouling modified the membrane surface, making the membrane surface more heterogeneous and more hydrophobic.

  15. Effect of cyclic aeration on fouling in submerged membrane bioreactor for wastewater treatment.

    Science.gov (United States)

    Wu, Jun; He, Chengda

    2012-07-01

    Due to the inefficiency of aeration measures in preventing fouling by soluble and colloidal particles. The effect of alternating high/low cyclic aeration mode on the membrane fouling in the submerged membrane bioreactor was studied by comparing to fouling in a constant aeration mode. Results indicated a higher overall fouling rate in the cyclic aeration mode than in the constant aeration. However, a higher percentage of reversible fouling was observed for the cyclic aeration mode. The membrane permeability can be more easily recovered from physical cleaning such as backwashing in the cyclic aeration mode. The activated sludge floc size distribution analysis revealed a floc destruction and re-flocculation processes caused by the alternating high/low aeration. The short high aeration period could prevent the destruction of strong strength bonds within activated sludge flocs. Therefore, less soluble and colloidal material was observed in the supernatant due to the preservation of the strong strength bonds. The weak strength bonds damaged in the high aeration period could be recovered in the re-flocculation process in the low aeration period. The floc destruction and re-flocculation processes were suggested to be the main reason for the low irreversible fouling in the cyclic aeration mode.

  16. Membrane foulants and fouling mechanisms in microfiltration and ultrafiltration of an activated sludge effluent.

    Science.gov (United States)

    Nguyen, S T; Roddick, F A; Harris, J L

    2010-01-01

    Membrane fouling in microfiltration (MF) and ultrafiltration (UF) of an activated sludge (AS) effluent was investigated. It was found that the major membrane foulants were polysaccharides, proteins, polysaccharide-like and protein-like materials and humic substances. MF fouling by the raw effluent was governed by pore adsorption of particles smaller than the pores during the first 30 minutes of filtration and then followed the cake filtration model. UF fouling could be described by the cake filtration model throughout the course of filtration. Coagulation with alum and (poly)aluminium chlorohydrate (ACH) altered the MF fouling mechanism to follow the cake filtration model from the beginning of filtration. The MF and UF flux improvement by coagulation was due to the removal of some of the foulants in the raw AS effluent by the coagulants. The MF flux improvement was greater for alum than for ACH whereas the two coagulants performed equally well in UF. Coagulation also reduced hydraulically irreversible fouling on the membranes and this effect was more prominent in MF than in UF. The unified membrane fouling index (UMFI) was used to quantitatively evaluate the effectiveness of coagulation on membrane flux enhancement.

  17. A crossflow filtration system for constant permeate flux membrane fouling characterization

    Science.gov (United States)

    Miller, Daniel J.; Paul, Donald R.; Freeman, Benny D.

    2013-03-01

    Membrane fouling is often characterized using a crossflow filtration apparatus. Typically, the transmembrane pressure (TMP) difference is fixed, and the flux is allowed to decline as the membrane fouls and the resistance to mass transfer increases. However, as flux varies, so too does the rate at which foulants are brought to the membrane surface, so the observed fouling behavior is not solely the result of membrane/foulant interactions. Constant flux experiments, where the permeate flux is fixed and the TMP difference varies, minimize such variations in the hydrodynamic conditions at the membrane surface, but constant TMP difference experiments dominate the fouling literature because they are more straightforward to execute than constant flux experiments. Additionally, most industrial water purification membrane installations operate at constant flux rather than at constant TMP. Here, we describe the construction and operation of a constant flux crossflow fouling apparatus. System measurement accuracy was validated by comparison of pure water permeance measurements to values specified by the membrane manufacturer, reported elsewhere, and measured by another technique. Fouling experiments were performed with two membrane/foulant systems: polysulfone ultrafiltration membranes with a soybean oil emulsion foulant and PVDF microfiltration membranes with a polystyrene latex bead suspension foulant. Automatic permeate flux control facilitated flux stepping experiments, which are commonly used to determine the threshold flux or critical flux of a membrane/foulant pair. Comparison of a flux stepping experiment with a literature report yielded good agreement.

  18. Crystallization fouling of finned tubes during pool boiling: effect of fin density

    Energy Technology Data Exchange (ETDEWEB)

    Esawy, M.; Malayeri, M.R. [University of Stuttgart, Institute for Thermodynamics and Thermal Engineering (ITW), Stuttgart (Germany); Mueller-Steinhagen, H. [University of Stuttgart, Institute for Thermodynamics and Thermal Engineering (ITW), Stuttgart (Germany); German Aerospace Centre (DLR), Institute of Technical Thermodynamics, Stuttgart (Germany)

    2010-11-15

    Bubble characteristics such as density, size, frequency and motion are key factors that contribute to the superiority of nucleate pool boiling over other modes of heat transfer. Nevertheless, if heat transfer occurs in an environment prone to fouling, the very same parameters may lead to accelerated deposit formation due to concentration effects beneath the growing bubbles. This has led to the widely accepted design recommendation to maintain the heat transfer surface temperature below the boiling point if fouling may occur, e.g., in seawater desalination. The present paper aims at investigating the formation of deposits on finned tubes during nucleate pool boiling of CaSO{sub 4} solutions. The test finned tubes are low finned tubes with fin densities of 19 and 26 fins/in. made from Cu-Ni. The fouling experiments were carried out at atmospheric pressure for different heat fluxes ranging from 100 to 300 kW/m{sup 2} and a CaSO{sub 4} concentration of 1.6 g/L. For the sake of comparison, similar runs were performed with smooth stainless steel tubes. The results show that: (1) the fouling resistance decreases with increasing fin density, (2) fouling on the finned tubes was reduced with increasing nucleate boiling activity and (3) if any fouling layer occurred on the finned tubes it could be removed easily. (orig.)

  19. In-situ non-invasive device for early detection of fouling in aquatic systems

    KAUST Repository

    Fortunato, Luca

    2017-01-05

    An in-situ, non-destructive sensor device, system and method are provided to detect or assess fouling at a very early stage of development. They can be used to detect or assess fouling on a surface of an aquatic system. They can be used to obtain a depth profile of the fouling. Data concerning the depth profile can be extracted and used to assess the fouling on the surface, in one or more aspects, the method can include providing an optical tomography spectrometer; optically positioning the optical tomography spectrometer in association with a surface of an area to be assessed for fouling in an aqueous system; irradiating the surface; acquiring, from irradiating the surface, a plurality of signals as a function of a distance from the surface at different times; extracting data from the signals as a function of the distance to obtain a depth profile of the surface at the different times; and determining a change in the depth profile between the different times to assess fouling on the surface.

  20. Discrete element method analysis of lateral resistance of fouled ballast bed

    Institute of Scientific and Technical Information of China (English)

    徐旸; 高亮; 张艳荣; 尹辉; 蔡小培

    2016-01-01

    The lateral resistance of sleeper plays an important role in ensuring the stability of a railway track, which may change in the operation of railway, due to the fouling in the ballast bed. In this work, discrete element method was adopted to investigate the effect of fouling on the lateral resistance of sleeper. The shape information of ballast was captured by method of three-dimensional vision reconstruction. In order to calibrate the mechanical parameters and verify the models, a lateral resistance field test was carried out by using a custom-made device. The contact force distributions in the different parts of sleeper as well as the interaction between ballast and sleeper were discussed in depth. The results show that fouling of ballast bed evidently reduces the lateral resistance of sleeper and the decreasing degree is also related to the fouled position of ballast bed, in the order of shoulder > bottom > side. Therefore, the effect of fouling, especially the fouling in the ballast shoulder, on the lateral resistance of sleeper, should be taken into account in ballast track maintenance work.

  1. Nanopatterned antimicrobial enzymatic surfaces combining biocidal and fouling release properties

    Science.gov (United States)

    Yu, Qian; Ista, Linnea K.; López, Gabriel P.

    2014-04-01

    Surfaces incorporating the antimicrobial enzyme, lysozyme, have been previously demonstrated to effectively disrupt bacterial cellular envelopes. As with any surface active antimicrobial, however, lysozyme-expressing surfaces become limited in their utility by the accumulation of dead bacteria and debris. Surfaces modified with environmentally responsive polymers, on the other hand, have been shown to reversibly attach and release both live and dead bacterial cells. In this work, we combine the antimicrobial activity of lysozyme with the fouling release capability of the thermally responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), which has a lower critical solution temperature (LCST) in water at ~32 °C. Nanopatterned PNIPAAm brushes were fabricated using interferometric lithography followed by surface-initiated polymerization. Lysozyme was then adsorbed into the polymer-free regions of the substrate between the brushes to achieve a hybrid surface with switchable antimicrobial activity and fouling-release ability in response to the change of temperature. The temperature triggered hydration and conformational change of the nanopatterned PNIPAAm brushes provide the ability to temporally regulate the spatial concealment and exposure of adsorbed lysozyme. The biocidal efficacy and release properties of the hybrid surface were tested against Escherichia coli K12 and Staphylococcus epidermidis. The hybrid surfaces facilitated the attachment of bacteria at 37 °C for E. coli and 25 °C for S. epidermidis and when the temperature is above the LCST, collapsed and dehydrated PNIPAAm chains expose lysozyme to kill attached bacteria. Changing temperature across the LCST of PNIPAAm (e.g. from 37 °C to 25 °C for E. coli or from 25 °C to 37 °C for S. epidermidis) to induce a hydration transition of PNIPAAm promoted the release of dead bacteria and debris from the surfaces upon mild shearing. These results suggest that nano-engineered surfaces can provide an effective

  2. Source water quality shaping different fouling scenarios in a full-scale desalination plant at the Red Sea

    KAUST Repository

    Khan, Muhammad

    2013-02-01

    The complexity of Reverse Osmosis (RO) membrane fouling phenomenon has been widely studied and several factors influencing it have been reported by many researchers. This original study involves the investigation of two different fouling profiles produced at a seawater RO desalination plant installed on a floating mobile barge. The plant was moved along the coastline of the Red Sea in Saudi Arabia. The two locations where the barge was anchored showed different water quality. At the second location, two modules were harvested. One of the modules was pre-fouled by inorganics during plant operation at the previous site while the other was installed at the second site. Fouled membranes were subjected to a wide range of chemical and microbiological characterization procedures. Drastically different fouling patterns were observed in the two membranes which indicates the influence of source water quality on membrane surface modification and on fouling of RO membranes. © 2012 Elsevier Ltd.

  3. Evaluation of fouling formation and evolution on hollow fibre membrane: effects of ageing and chemical exposure on biofoulant.

    Science.gov (United States)

    Xu, Qianhui; Ye, Yun; Chen, Vicki; Wen, Xianghua

    2015-01-01

    Bio-deposition and biofouling, a major challenge for membrane filtration, is still not fully understood due to its complex structure and intricate evolution with time and chemical environment. In this work, diluted sludge from an anaerobic bioreactor with low mixed liquor suspended solid (MLSS) concentration was filtered for 3.5 h to form initial fouling layers which were then exposed to various solution environments for 17 h. Apart from monitoring the hydraulic resistance of membrane fouling, a real time direct observation (DO) technique was applied to monitor the change of thickness in the fouling layer. The cohesion and adhesion of different fouling layer were investigated by monitoring the transmembrane pressure (TMP) and thickness change after applying relaxation (cessation of filtration) and backwash. It was found that TMPs and resistances of the aged fouling layers increased significantly after 17 h filtration. All the aged fouling layers exhibited lower compressibility as a result of more soluble microbial products (SMP) and extracellular polymeric substances (EPS) excretion, biofilm growth. From in situ imaging, the fouling on the membrane surface appeared to be inhomogeneous from the inner (lumen) surface outwards. During long term filtration of fouling layer with Milli-Q water, direct observation (DO) results indicated the reorganization of the fouling layer in terms of peeling, rolling over and re-depositing on the membrane surface, resulting into more compressed fouling layers with higher resistances. Confocal Laser Scanning Microscopy (CLSM) analysis of aged fouling layers also indicated that the dead/total ratio of microorganisms was not uniform and increased gradually from the bottom to the top of the fouling layers.

  4. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong

    2014-02-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.

  5. FOULING CHARACTERIZATION OF MEMBRANE CONTACTORS USED FOR THE RECOVERY AND CONCENTRATION OF AMMONIA FROM UNDIGESTED PIG SLURRY

    DEFF Research Database (Denmark)

    Zarebska, Agata; Norddahl, Birgir; Christensen, Knud Villy

    2012-01-01

    The main obstacle impeding implementation of membrane contactors for the recovery and concentration of ammonia from swine manure is the phenomena of membrane fouling. Fouling is defined as the accumulation of suspended or dissolved substances on the membrane surface and/or within its pores. Due...... a week of running the contactor without cleaning. This indicates that fouling could be a severe problem. The intensity of fouling can be reduced by feed pretreatment and by optimizing the operating conditions of the membrane contactor. This will also facilitate removal of ammonia....

  6. Model-based analysis of the effect of different operating conditions on fouling mechanisms in a membrane bioreactor.

    Science.gov (United States)

    Sabia, Gianpaolo; Ferraris, Marco; Spagni, Alessandro

    2016-01-01

    This study proposes a model-based evaluation of the effect of different operating conditions with and without pre-denitrification treatment and applying three different solids retention times on the fouling mechanisms involved in membrane bioreactors (MBRs). A total of 11 fouling models obtained from literature were used to fit the transmembrane pressure variations measured in a pilot-scale MBR treating real wastewater for more than 1 year. The results showed that all the models represent reasonable descriptions of the fouling processes in the MBR tested. The model-based analysis confirmed that membrane fouling started by pore blocking (complete blocking model) and by a reduction of the pore diameter (standard blocking) while cake filtration became the dominant fouling mechanism over long-term operation. However, the different fouling mechanisms occurred almost simultaneously making it rather difficult to identify each one. The membrane "history" (i.e. age, lifespan, etc.) seems the most important factor affecting the fouling mechanism more than the applied operating conditions. Nonlinear regression of the most complex models (combined models) evaluated in this study sometimes demonstrated unreliable parameter estimates suggesting that the four basic fouling models (complete, standard, intermediate blocking and cake filtration) contain enough details to represent a reasonable description of the main fouling processes occurring in MBRs.

  7. Influence of hydrophobic/hydrophilic fractions of extracellular organic matters of Microcystis aeruginosa on ultrafiltration membrane fouling.

    Science.gov (United States)

    Zhou, Shiqing; Shao, Yisheng; Gao, Naiyun; Li, Lei; Deng, Jing; Tan, Chaoqun; Zhu, Mingqiu

    2014-02-01

    Fouling is a major obstacle to maintain the efficiency of ultrafiltration-based drinking water treatment process. Algal extracellular organic matters (EOMs) are currently considered as one of the major sources of membrane fouling. The objective of this study was to investigate the influence of different hydrophobic/hydrophilic fractions of EOM extracted from Microcystis aeruginosa on ultrafiltration membrane fouling at lab scale. The experimental data indicated that EOM exhibited similar flux decline trends on polyethersulfone (PES) and regenerated cellulose (RC) membranes but caused greater irreversible fouling on PES membrane than RC membrane due to its hydrophobic property. It was also observed that charged hydrophilic (CHPI) and neutral hydrophilic (NHPI) fractions caused greater flux decline over hydrophobic (HPO) and transphilic (TPI) fractions. For PES membrane, the order of the irreversible fouling potentials for the four fractions was HPO>TPI>CHPI>NHPI, while the irreversible fouling potentials of RC membrane were tiny and could be ignored. Fluorescence excitation-emission matrix (EEM) spectra and Fourier transform infrared (FTIR) spectra suggested that protein-like, polysaccharide-like and humic-like substances were the major components responsible for membrane fouling. The results also indicated that the irreversible fouling increased as the pH decreased. The addition of calcium to feed solutions led to more severe flux decline and irreversible fouling.

  8. High throughput discovery of new fouling-resistant surfaces†

    Science.gov (United States)

    Zhou, Mingyan; Liu, Hongwei; Venkiteshwaran, Adith; Kilduff, James; Anderson, Daniel G.; Langer, Robert; Belfort, Georges

    2017-01-01

    A novel high throughput method for synthesis and screening of customized protein-resistant surfaces was developed. This method is an inexpensive, fast, reproducible and scalable approach to synthesize and screen protein-resistant surfaces appropriate for a specific feed. The method is illustrated here by combining a high throughput platform (HTP) approach together with our patented photo-induced graft polymerization (PGP) method developed for facile modification of commercial poly(aryl sulfone) membranes. We demonstrate that the HTP–PGP approach to synthesize and screen fouling-resistant surfaces is general, and thus provides the capability to develop surfaces optimized for specific feeds. Surfaces were prepared via graft polymerization onto poly(ether sulfone) (PES) membranes and were evaluated using a protein adsorption assay followed by pressure-driven filtration. We have employed the HTP–PGP approach to confirm previously reported successful monomers and to develop new antifouling surfaces from a library of 66 monomers for four different challenges of interest to the biotechnology community: hen egg-white lysozyme, supernatant from Chinese Hamster Ovary (CHO) cells in phosphate buffered saline (PBS) solution as a model cell suspension, and immunoglobulin G (IgG) precipitated in the absence and presence of bovine serum albumin (BSA) in high salt solution as a model precipitation process.

  9. Sedimentation and fouling of optical surfaces at the ANTARES site

    Science.gov (United States)

    ANTARES Collaboration; CAU CEFREM Collaboration; Amram, P.; Anghinolfi, M.; Anvar, S.; Ardellier-Desages, F. E.; Aslanides, E.; Aubert, J.-J.; Azoulay, R.; Bailey, D.; Basa, S.; Battaglieri, M.; Bellotti, R.; Beltramelli, J.; Benhammou, Y.; Berthier, R.; Bertin, V.; Billault, M.; Blaes, R.; Bland, R. W.; Blondeau, F.; de Botton, N.; Boulesteix, J.; Brooks, C. B.; Brunner, J.; Cafagna, F.; Calzas, A.; Capone, A.; Caponetto, L.; Cârloganu, C.; Carmona, E.; Carr, J.; Cartwright, S. L.; Cecchini, S.; Ciacio, F.; Circella, M.; Compère, C.; Cooper, S.; Coyle, P.; Cuneo, S.; Danilov, M.; van Dantzig, R.; de Marzo, C.; Destelle, J.-J.; de Vita, R.; Dispau, G.; Druillole, F.; Engelen, J.; Feinstein, F.; Ferdi, C.; Festy, D.; Fopma, J.; Gallone, J.-M.; Giacomelli, G.; Goret, P.; Gournay, J.-F.; Hallewell, G.; Heijboer, A.; Hernández-Rey, J. J.; Hubbard, J. R.; Jaquet, M.; de Jong, M.; Karolak, M.; Keller, P.; Kooijman, P.; Kouchner, A.; Kudryavtsev, V. A.; Lafoux, H.; Lagier, P.; Lamare, P.; Languillat, J.-C.; Laubier, L.; Laugier, J.-P.; Leilde, B.; Le Provost, H.; Le van Suu, A.; Lo Nigro, L.; Lo Presti, D.; Loucatos, S.; Louis, F.; Lyashuk, V.; Magnier, P.; Marcelin, M.; Margiotta, A.; Masullo, R.; Mazéas, F.; Mazeau, B.; Mazure, A.; McMillan, J. E.; Migneco, E.; Millot, C.; Mols, P.; Montanet, F.; Montaruli, T.; Moscoso, L.; Musumeci, M.; Nezri, E.; Nooren, G. J.; Oberski, J. E. J.; Olivetto, C.; Oppelt-Pohl, A.; Palanque-Delabrouille, N.; Papaleo, R.; Payre, P.; Perrin, P.; Petruccetti, M.; Petta, C.; Piattelli, P.; Poinsignon, J.; Potheau, R.; Queinec, Y.; Racca, C.; Raia, G.; Randazzo, N.; Rethore, F.; Riccobene, G.; Ricol, J.-S.; Ripani, M.; Roca-Blay, V.; Romeyer, A.; Rostovstev, A.; Russo, G. V.; Sacquin, Y.; Salusti, E.; Schuller, J.-P.; Schuster, W.; Soirat, J.-P.; Souvorova, O.; Spooner, N. J. C.; Spurio, M.; Stolarczyk, T.; Stubert, D.; Taiuti, M.; Tao, C.; Thompson, L. F.; Tilav, S.; Triay, R.; Usik, A.; Valdy, P.; Valente, V.; Varlamov, I.; Vaudaine, G.; Vernin, P.; Vladimirsky, E.; Vorobiev, M.; de Witt Huberts, P.; de Wolf, E.; Zakharov, V.; Zavatarelli, S.; Zornoza, Juan de Dios; Zún~Iga, J.; Aloïsi, J.-C.; Kerhervé, Ph.; Monaco, A.

    2003-05-01

    ANTARES is a project leading towards the construction and deployment of a neutrino telescope in the deep Mediterranean Sea. The telescope will use an array of photomultiplier tubes to detect the Cherenkov light emitted by muons resulting from the interaction with matter of high energy neutrinos. In the vicinity of the deployment site the ANTARES Collaboration has performed a series of in situ measurements to study the change in light transmission through glass surfaces during immersions of several months. The average loss of light transmission is estimated to be only ~2% at the equator of a glass sphere one year after deployment. It decreases with increasing zenith angle, and tends to saturate with time. The transmission loss, therefore, is expected to remain small for the several year lifetime of the ANTARES detector whose optical modules are oriented downwards. The measurements were complemented by the analysis of the 210Pb activity profile in sediment cores and the study of biofouling on glass plates. Despite a significant sedimentation rate at the site, in the 0.02-0.05 cmyr-1 range, the sediments adhere loosely to the glass surfaces and can be washed off by water currents. Further, fouling by deposits of light-absorbing particulates is only significant for surfaces facing upwards.

  10. Organic fouling behavior of superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membranes functionalized with surface-tailored nanoparticles: Implications for organic fouling in membrane bioreactors

    KAUST Repository

    Liang, Shuai

    2014-08-01

    This study systematically investigates the organic fouling behavior of a superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membrane functionalized via post-fabrication tethering of surface-tailored silica nanoparticles to poly(methacrylic acid)-grafted PVDF membrane surface. Sodium alginate (SA), Suwannee River natural organic matter (SRNOM), and bovine serum albumin (BSA) were used as model organic foulants to investigate the antifouling behavior of the superhydrophilic membrane with combined-fouling (mixture of foulants) and individual-fouling (single foulant) tests. A membrane bioreactor (MBR) plant supernatant was also used to verify the organic antifouling property of the superhydrophilic membrane under realistic conditions. Foulant size distributions and foulant-membrane interfacial forces were measured to interpret the observed membrane fouling behavior. Molecular weight cutoff measurements confirmed that membrane functionalization did not adversely affect the intrinsic membrane selectivity. Both filtration tests with the synthetic foulant-mixture solution (containing SA, SRNOM, and BSA) and MBR plant supernatant demonstrated the reliability and durability of the antifouling property of the superhydrophilic membrane. The conspicuous reduction in foulant-membrane interfacial forces for the functionalized membrane further verified the antifouling properties of the superhydrophilic membrane, suggesting great potential for applications in wastewater treatment. © 2014 Elsevier B.V.

  11. A physicochemical investigation of membrane fouling in cold microfiltration of skim milk.

    Science.gov (United States)

    Tan, T J; Wang, D; Moraru, C I

    2014-01-01

    The main challenge in microfiltration (MF) is membrane fouling, which leads to a significant decline in permeate flux and a change in membrane selectivity over time. This work aims to elucidate the mechanisms of membrane fouling in cold MF of skim milk by identifying and quantifying the proteins and minerals involved in external and internal membrane fouling. Microfiltration was conducted using a 1.4-μm ceramic membrane, at a temperature of 6±1°C, cross-flow velocity of 6m/s, and transmembrane pressure of 159kPa, for 90min. Internal and external foulants were extracted from a ceramic membrane both after a brief contact between the membrane and skim milk, to evaluate instantaneous adsorption of foulants, and after MF. Four foulant streams were collected: weakly attached external foulants, weakly attached internal foulants, strongly attached external foulants, and strongly attached internal foulants. Liquid chromatography coupled with tandem mass spectrometry analysis showed that all major milk proteins were present in all foulant streams. Proteins did appear to be the major cause of membrane fouling. Proteomics analysis of the foulants indicated elevated levels of serum proteins as compared with milk in the foulant fractions collected from the adsorption study. Caseins were preferentially introduced into the fouling layer during MF, when transmembrane pressure was applied, as confirmed both by proteomics and mineral analyses. The knowledge generated in this study advances the understanding of fouling mechanisms in cold MF of skim milk and can be used to identify solutions for minimizing membrane fouling and increasing the efficiency of milk MF.

  12. Membrane fouling and anti-fouling strategies using RO retentate from a municipal water recycling plant as the feed for osmotic power generation.

    Science.gov (United States)

    Chen, Si Cong; Amy, Gary L; Chung, Tai-Shung

    2016-01-01

    RO retentate from a municipal water recycling plant is considered as a potential feed stream for osmotic power generation in this paper. The feasibility of using RO retentate from a municipal water recycling plant was examined from two aspects: (a) the membrane fouling propensity of RO retentate, and (b) the efficacy of anti-fouling strategies. The membranes used in this study were the inner selective thin film composite polyethersulfone (TFC/PES) hollow fiber membranes, which possessed a high water permeability and good mechanical strength. Scaling by phosphate salts was found to be one possible inorganic fouling on the innermost layer of the PES membrane, whereas silica fouling was observed to be the governing fouling on the outmost surface of the PES membrane. Two anti-fouling pretreatments, i.e., pH adjustment and anti-scalant pre-treatment for the feed stream, were studied and found to be straightforward and effective. Using RO retentate at pH 7.2 as the feed and 1 M NaCl as the draw solution, the average power density was 7.3 W/m(2) at 20 bar. The average power density increased to 12.6 W/m(2) by modifying RO retentate with an initial pH value of 5.5 using HCl and to 13.4 W/m(2) by adding 1.1 mM ethylenediaminetetraacetic acid (EDTA). Moreover, the flux recovery of the fouled membranes, without the indicated pretreatments, reached 84.9% using deionized (DI) water flushing and 95.0% using air bubbling under a high crossflow velocity of 23.3 cm/s (Re = 2497) for 30 min. After pretreatment by pH adjustment, the flux recovery increased to 94.6% by DI water flushing and 100.0% by air bubbling. After pretreatment by adding 1.1 mM EDTA into RO retentate, flux was almost fully restored by physical cleaning by DI water flushing and air bubbling. These results provide insight into developing an effective pretreatment by either pH adjustment or EDTA addition before PRO and physical cleaning methods by DI water flushing and air bubbling for membrane used in

  13. Membrane fouling and anti-fouling strategies using RO retentate from a municipal water recycling plant as the feed for osmotic power generation

    KAUST Repository

    Chen, Si Cong

    2015-10-25

    RO retentate from a municipal water recycling plant is considered as a potential feed stream for osmotic power generation in this paper. The feasibility of using RO retentate from a municipal water recycling plant was examined from two aspects: (a) the membrane fouling propensity of RO retentate, and (b) the efficacy of anti-fouling strategies. The membranes used in this study were the inner selective thin film composite polyethersulfone (TFC/PES) hollow fiber membranes, which possessed a high water permeability and good mechanical strength. Scaling by phosphate salts was found to be one possible inorganic fouling on the innermost layer of the PES membrane, whereas silica fouling was observed to be the governing fouling on the outmost surface of the PES membrane. Two anti-fouling pretreatments, i.e., pH adjustment and anti-scalant pre-treatment for the feed stream, were studied and found to be straightforward and effective. Using RO retentate at pH 7.2 as the feed and 1 M NaCl as the draw solution, the average power density was 7.3 W/m at 20 bar. The average power density increased to 12.6 W/m by modifying RO retentate with an initial pH value of 5.5 using HCl and to 13.4 W/m by adding 1.1 mM ethylenediaminetetraacetic acid (EDTA). Moreover, the flux recovery of the fouled membranes, without the indicated pretreatments, reached 84.9% using deionized (DI) water flushing and 95.0% using air bubbling under a high crossflow velocity of 23.3 cm/s (Re = 2497) for 30 min. After pretreatment by pH adjustment, the flux recovery increased to 94.6% by DI water flushing and 100.0% by air bubbling. After pretreatment by adding 1.1 mM EDTA into RO retentate, flux was almost fully restored by physical cleaning by DI water flushing and air bubbling. These results provide insight into developing an effective pretreatment by either pH adjustment or EDTA addition before PRO and physical cleaning methods by DI water flushing and air bubbling for membrane used in osmotic power

  14. Effects of fluid flowrate on coconut milk fouling at pasteurization temperature (70ºC - 74.5ºC

    Directory of Open Access Journals (Sweden)

    Suvit Tia

    2006-11-01

    Full Text Available Effects of fluid flowrate on coconut milk fouling at pasteurization temperature (heating from 70ºC to 74.5ºC were investigated. A test section equipped with four flat plates forming one coconut milk channel and two hot water channels was constructed with the total heat transfer area of 0.051 m2. Three different flowrates of coconut milk (2, 4 and 6 litres per minute (LPM were studied. Monitoring of the overall heat transfer coefficient (U with time (t and the rate of increase of the fouling resistance (dRf/dt was done for all experimental runs. The results illustrated that there were two fouling periods: a fouling period and a post-fouling period, where the rate of increase of the fouling resistance of the fouling period was found to be higher than that of the post-fouling period. The effects of fluid flowrate were found to increase the fouling rate when the flowrate decreased. Published fouling models by protein solutions were unable to predict accurately the fouling rate for coconut milk. Non-linear regression models were then provided by using the experimental data to illustrate the effects of fluid flowrate on coconut milk fouling. The role of protein and fat on coconut milk fouling was explained according to microanalysis of the deposit and chemistry data of the coconut milk from previous research.

  15. Microfiltration of different surface waters with/without coagulation: clear correlations between membrane fouling and hydrophilic biopolymers.

    Science.gov (United States)

    Kimura, Katsuki; Tanaka, Ken; Watanabe, Yoshimasa

    2014-02-01

    Although low-pressure membranes (microfiltration (MF) or ultrafiltration (UF)) have become viable options for drinking water treatment, problems caused by membrane fouling must still be addressed. The objective of this study was to compare five different surface waters and to identify a relevant index of water quality that can be used for prediction of the fouling potential of the water. Bench-scale filtration tests were carried out with commercially available hollow-fiber MF membranes. Fairly long-term (a few days) filtrations in the constant-flow mode were carried out with automatic backwash. Membrane fouling in this study was shown to be irreversible as a result of the periodic backwash carried out throughout of the operation. Easily accessible indexes of water quality including dissolved organic carbon (DOC), UV absorbance, Ca concentration and turbidity could not explain the degree of fouling encountered in the filtration tests. Fluorescence excitation-emission matrix (EEM) could provide information on the presence of protein-like substances in water, and peaks for protein showed some correlation with the membrane fouling. Biopolymer (characterized by high molecular weights and insensitivity to UV light absorption) concentrations in the five waters determined by liquid chromatography with organic carbon detection (LC-OCD) exhibited an excellent correlation with the fouling rates. Coagulation with polyaluminum chloride could mitigate membrane fouling in all cases. The extent of fouling seen with coagulated waters was also correlated with biopolymer concentrations. The relationship between biopolymer concentrations and the fouling rates established for the raw waters could also be applied to the coagulated waters. These results suggested that the contribution of biopolymers to membrane fouling in the present study was significant, an observation that was supported by the analysis of foulants extracted at the termination of each test. Biopolymer concentrations

  16. Membrane fouling and dialysate flow pattern in an internal filtration-enhancing dialyzer.

    Science.gov (United States)

    Yamamoto, Ken-ichiro; Hiwatari, Michihito; Kohori, Fukashi; Sakai, Kiyotaka; Fukuda, Makoto; Hiyoshi, Tatsuo

    2005-01-01

    For efficient removal of large molecular weight solutes by dialysis, several types of internal filtration-enhancing dialyzers (IFEDs) are commercially available. However, in a pressure-driven membrane separation process (i.e., filtration), membrane fouling caused by adhesion of plasma proteins is a severe problem. The objective of the present study is to investigate the effects of internal filtration on membrane fouling based on the membrane's pure-water permeability, diffusive permeability, and sieving coefficient. Hemodialysis experiments were performed with two different dialyzers, IFEDs and non-IFEDs. Local membrane fouling in each dialyzer was evaluated by measuring the pure-water permeability, the diffusive permeability, and the sieving coefficient of native membranes and membranes treated with bovine blood. The effects of packing ratio on dialysate flow pattern were also evaluated by measuring the time required for an ion tracer to reach electrodes placed in the dialyzers. In the IFED, membrane fouling caused by protein adhesion is increased because of enhanced internal filtration only at the early stage of dialysis, and this fouling tends to occur only near the dialysate outlet port. However, enhanced internal filtration has little effect on measured membrane transfer parameters.

  17. FLUX PROFILES AND MATHEMATICAL MODELING OF FOULING MECHANISM FOR ULTRAFILTRATION OF KONJAC GLUCOMANNAN

    Directory of Open Access Journals (Sweden)

    NITA ARYANTI

    2016-07-01

    Full Text Available This study was focused on principles and fouling analysis of konjac glucomannan (KGM separation using ultrafiltration system. Two Polyethersulfone membranes (PES having molecular weight cut-off of 10 and 20 kDa were used. It was found that membrane having larger pore size provided higher flux profiles. Evaluation of different transmembrane pressures resulted on possibility of more severe fouling at higher membrane pressure. With the increase of konjac glucomannan concentration, decrease of profile flux was observed. Further, a simple mathematical modelling of fouling mechanism was analyzed based on Hermia’s model. The images of membrane surfaces and cross-sections obtained by scanning electron microscopy (SEM were examined and being compared with the model. The research found that the fouling mechanisms of KGM ultrafiltration using membrane with pore size of 10 kDa was complete blocking. On the contrary, cake/gel layer formation was a fouling mechanism for ultrafiltration system with pore size of 20kDa.

  18. Novel Fouling-Reducing Coatings for Ultrafiltration, Nanofiltration, and Reverse Osmosis Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Benny Freeman

    2008-08-31

    Polymeric membranes could potentially be the most flexible and viable long-term strategy for treatment of produced water from oil and gas production. However, widespread use of membranes, including reverse osmosis (RO) membranes, for produced water purification is hindered due to fouling caused by the impurities present in the water. Fouling of RO membranes is likely caused by surface properties including roughness, hydrophilicity, and charge, so surface modification is the most widely considered approach to improve the fouling properties of current RO membranes. This project focuses on two main approaches to surface modification: coating and grafting. Hydrophilic coating and grafting materials based on poly(ethylene glycol) (PEG) are applied to commercial RO membranes manufactured by Dow FilmTec and GE. Crossflow filtration experiments are used to determine the fouling resistance of modified membranes, and compare their performance to that of unmodified commercial RO membranes. Grafting and coating are shown to be two alternative methods of producing modified membranes with improved fouling resistance.

  19. Distribution and deposition of organic fouling on the microfiltration membrane evaluated by high-frequency ultrasound.

    Science.gov (United States)

    Lin, Yi-Hsun; Tung, Kuo-Lun; Wang, Shyh-Hau; Zhou, Qifa; Shung, K Kirk

    2013-04-15

    A 50 MHz high-frequency ultrasound and analysis method were developed to further improve the in situ assessment of deposition and distribution of organic fouling on the polyvinylidene fluoride (PVDF) membranes. Measurements of fouling depositions were performed from PVDF membranes filtrated with aqueous humic acid solutions (HAS) of 2 and 4 ppm concentrations in a flat-sheet module. Ultrasound signals reflected from the PVDF membranes, following filtrations at various durations including 0, 5, 15, 30, 60, and 100 min, were acquired. The thickness and distribution of fouling estimated and assessed by peak-to-peak echo voltage (Vpp) and C-mode images were found to be non-homogeneously deposited on the membranes. Following the filtrations with 2 and 4 ppm HAS for 100 min, the corresponding thickness of fouling deposition increased from 1.81±9 to 2.4571.57 mm, respectively; those average Vpp decreased from 2.05±07 to 1.13±16 V and from 2.11±08 to 0.94±15 V. These results demonstrated that the deposition and distribution of organic fouling could be sensitively and rapidly evaluated by high-frequency ultrasound image incorporated with the analysis method.

  20. Influence of biofilm carriers on membrane fouling propensity in moving biofilm membrane bioreactor.

    Science.gov (United States)

    Jamal Khan, S; Zohaib-Ur-Rehman; Visvanathan, C; Jegatheesan, V

    2012-06-01

    In moving biofilm membrane bioreactor (MB-MBR) sponge carriers for biofilm growth were coupled with conventional submerged membrane bioreactor (C-MBR). This study compared the fouling propensity of C-MBR with MB-MBR and investigated factors affecting fouling variations in both the systems. Membrane fouling tendencies were monitored in terms of trans-membrane pressure (TMP) and the fouling characterization included membrane fouling resistances in situ and specific cake resistance (SCR) in batch filtration cell. Comparison of TMP profiles depicted prolong filtration periods in MB-MBR. Cake layer resistance (R(c)), pore blocking resistance (R(p)) as well as SCR were higher in C-MBR. The study reveals that hybrid biomass in MB-MBR creates relatively more porous cake structure in the absence of filamentous bacteria which were found in abundance in C-MBR. Filamentous bacteria were also responsible for the release of high concentration of carbohydrates in the form of soluble extra polymeric substance (EPS) contributing to higher R(p) in C-MBR.

  1. Physical–chemical properties, separation performance, and fouling resistance of mixed-matrix ultrafiltration membranes

    KAUST Repository

    Hoek, Eric M.V.

    2011-12-01

    Herein we report on the formation and characterization of mixed-matrix ultrafiltration (UF) membranes hand-cast by nonsolvent induced phase inversion. We evaluated nanometer-to-micrometer sized inorganic fillers (silver, copper, silica, zeolite, and silver-zeolite) materials with polysulfone (PSf) as the polymeric dispersing matrix. In general, mixed-matrix membranes were rougher, more hydrophilic, and more mechanically robust. Only sub-micron zeolite-PSf mixed-matrix membranes exhibited simultaneous improvements in water permeability and solute selectivity; all other mixed-matrix membranes were more permeable, but less selective due to defects associated with poor polymer-filler binding. Protein and bacterial fouling resistance of mixed-matrix membranes containing silver, zeolite, and silver-zeolite nanoparticles were compared to a low-fouling, poly(acrylonitrile) (PAN) UF membrane. Zeolite and silver containing membranes exhibited better protein fouling resistance (due to higher hydrophilicity), whereas silver and silver-zeolite based membranes produce better bacterial fouling resistance due to antimicrobial properties. Overall, zeolite-PSf and silver exchanged zeolite-PSf membranes offered the best combination of improved permeability, selectivity, and fouling resistance - superior to the commercial PAN membrane. © 2011 Elsevier B.V.

  2. Are anti-fouling effects in coralline algae species specific?

    Directory of Open Access Journals (Sweden)

    Alexandre Bigio Villas Bôas

    2004-03-01

    Full Text Available The crustose coralline algae are susceptible to be covered by other algae, which in turn can be affected by anti-fouling effects. In this study the hypothesis tested was that these algae can inhibit the growth of epiphytes in a species specific way. In the laboratory, propagules of Sargassum furcatum and Ulva fasciata were liberated and cultivated on pieces of coralline algae and slide covers (controls and their survival and growth were compared. Spongites and Hydrolithon significantly inhibited the growth of U. fasciata but not Sargassum. In the field, pieces of three species of live and dead coralline algae and their copies in epoxy putty discs were fixed on the rock. After one month epiphytic algae were identified and their dry mass quantified. Lithophyllum did not affect the epiphyte growth. In contrast Spongites and an unidentified coralline significantly inhibited the growth of Enteromorpha spp., Ulva fasciata and Hincksia mitchelliae. Colpomenia sinuosa was absent on all living crusts, but present on controls. Results show that the epiphyte-host relation depends on the species that are interacting. The sloughing of superficial cells of coralline crusts points to the possible action of physical anti-fouling effect, though a chemical one is not rejected.As algas calcárias crostosas são susceptíveis ao recobrimento por outras algas, entretanto, estas podem ser afetadas por efeitos anti-incrustantes. Neste estudo foi testada a hipótese de que estas algas possam inibir o crescimento somente de algumas espécies de epífitas. No laboratório, propágulos de Sargassum furcatum e Ulva fasciata foram liberados e cultivados sobre pedaços de algas calcárias e lamínulas de microscopia (controle e as suas sobrevivência e crescimento comparadas. Spongites e Hydrolithon inibiram significativamente o crescimento de U. fasciata, mas não de Sargassum. No campo, pedaços de três espécies de algas calcárias vivas, mortas e cópias destas em

  3. Surface chemistry interventions to control boiler tube fouling - Part II

    Energy Technology Data Exchange (ETDEWEB)

    Turner, C.W.; Guzonas, D.A.; Klimas, S.J

    2004-06-15

    This is the third in a series of reports from an investigation co-funded by the Electric Power Research Institute (EPRI) and by Atomic Energy of Canada Limited (AECL) into the effectiveness of alternative amines for controlling the rate of tube-bundle fouling under steam generator (SG) operating conditions. The objectives of this investigation are to determine whether the fouling rate depends on the amine used for pH control, to identify those factors that influence the effectiveness, and use this information to optimize the selection of an amine for chemistry control and deposit control in the steam cycle and steam generator, respectively. Work to date has demonstrated that the rate of particle deposition under steam generator operating conditions is strongly influenced by surface chemistry (Turner et al., 1997; Turner et al., 1999). This dependence upon surface chemistry is illustrated by the difference between the deposition rates measured for hematite and magnetite, and by the dependence of the particle deposition rate on the amine used for pH control. Deposition rates of hematite were found to be more than 10 times greater than those for magnetite under similar test conditions (Turner et al., 1997). At 270{sup o}C and pH{sub T} 6.2, the surfaces of hematite and magnetite are predicted to be positively charged and negatively charged, respectively (Shoonen, 1994). Measurements of the point of zero charge (PZC) of magnetite at temperatures from 25{sup o}C to 290{sup o}C by Wesolowski et al. (1999) have confirmed that magnetite is negatively charged at the stated conditions. A PZC of 4.2 was measured for Alloy 600 at 25{sup o}C (Balakrishnan and Turner, un-published results), and its surface is expected to remain negatively charged for alkaline chemistry over the temperature range of interest. Therefore, there will be a repulsive force between the surfaces of magnetite particles and Alloy 600 at 270{sup o}C and pH{sub T} 6.2 that is absent for hematite particles

  4. Membrane Fouling in Microfiltration of Sanitary Landfill Leachate for Removals of Colour and Solids

    Institute of Scientific and Technical Information of China (English)

    Emad S.M.Ameen; Abdullrahim Mohd Yusoff; Mohd Razman Salim; Azmi Aris; Aznah Nor Anuar

    2013-01-01

    In this research,the treatability of solids from sanitary landfill leachate by microfiltration membrane was investigated and the fouling of the membrane was carefully studied.Continuous microfiltration process was carried out for 21 h in experimental system involved coagulation with Moringa oleifera followed by filtration using submerged hollow fibre microfiltration membrane (MFM).Coagulation with M.Oleifera,air diffusers and back flush technique were used for preventing or alleviating fouling of the membrane.The hollow fibre MFM showed high removals of 98%,91% and 99% for turbidity,colour and total suspended solids respectively.It was obtained at the beginning of the filtration.However,quality of the filtrate rapidly declined during the filtration process.Fouling was found to proceed according to the classical cake filtration model.Coagulation with M.Oleifera as well asthe back-flush technique could not fully restore the deterioration occurred to the membrane.

  5. Effects of ionic strength on membrane fouling in a membrane bioreactor.

    Science.gov (United States)

    Wang, Fangyuan; Zhang, Meijia; Peng, Wei; He, Yiming; Lin, Hongjun; Chen, Jianrong; Hong, Huachang; Wang, Aijun; Yu, Haiying

    2014-03-01

    In this study, the effects of ionic strength on membrane fouling in a membrane bioreactor (MBR) were investigated. Ionic strength in range of 0.005-0.05mol/L exerted no apparent impacts on the resistance of virgin membrane, fouled membrane and pore clogging. Thermodynamic analysis showed existences of a secondary energy minimum and an energy barrier in the process of the sludge flocs approaching to membrane surface. Increase in ionic strength could significantly reduce the energy barrier. It was revealed that there existed a critical ionic strength above that the energy barrier would disappear, facilitating adhesion of the foulants. Cake resistance was not significantly affected by the ionic strength, but highly depended on SMP in supernatant. The high cake resistance caused by SMP could be explained by the osmotic pressure mechanism. The obtained results provided new insights into membrane fouling in MBRs.

  6. Comparison of membrane fouling during short-term filtration of aerobic granular sludge and activated sludge

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Aerobic granular sludge was cultivated adopting internal-circulate sequencing batch airlift reactor. The contradistinctive experiment about short-term membrane fouling between aerobic granular sludge system and activated sludge system were investigated. The membrane foulants was also characterized by Fourier Transform Infrared (FTIR) spectroscopy technique. The results showed that the aerobic granular sludge had excellent denitrification ability; the removal efficiency of TN could reach 90%. The aerobic granular sludge could alleviate membrane fouling effectively. The steady membrane flux of aerobic granular sludge was twice as much as that of activated sludge system. In addition, it was found that the aerobic granular sludge could result in severe membrane pore-blocking, however, the activated sludge could cause severe cake fouling. The major components of the foulants were identified as comprising of proteins and polysaccharide materials.

  7. Studies on the Ecology of Fouling Community in Daguanban Reclamation Area of Luoyuan Bay

    Institute of Scientific and Technical Information of China (English)

    周时强; 柯才焕; 林大鹏

    2001-01-01

    The test panels have been set for one year in the waters of Daguanban reclamation area of Luoyuan Bay to investigate the ecology of fouling community. 39 species of animals and 8 species of algae have been recorded during the investigation. The main period of settlement extends from May to October. The peak periods of biomass and covered area rate of the panels have been observed from Juneto September Balanus reticulatus, Bugula neritina, Molgula manhattensis, Tubularia mesembryanthemun and Enteromopha interstinalis are the dominant species in the fouling community. Species diversity index, species richness, species evenness and environmental factors are determined, the results of which indicate that water flow speed is the most important factor influencing the species and quantity composition of the fouling community.As to the mariculture production in the reclamation area, the main harmful period ranges from June to September.

  8. Mathematical models of membrane fouling in cross-flow micro-filtration

    Directory of Open Access Journals (Sweden)

    Mónica Jimena Ortíz Jerez

    2010-04-01

    Full Text Available The greatest difficulty arising during cross-flow micro-filtration is the formation of a cake layer on the membrane sur-face (also called fouling, thereby affecting system performance. Fouling has been related to permeate flux decay re-sulting from changes in operating variables. Many articles have been published in an attempt to explain this phe-nomenon but it has not yet been fully understood because it depends on specific solution/membrane interactions and differing parameters. This work was aimed at presenting an analytical review of recently published mathematical models to explain fouling. Although the reviewed models can be adjusted to any type of application, a simple “con-centration polarisation” model is advisable in the particular case of tropical fruit juices for describing the insoluble solids being deposited on membrane surface.

  9. Examinations of the crystallisation fouling in micro-structured heat exchangers; Untersuchungen zum Kristallisationsfouling in mikrostrukturierten Waermeuebertragern

    Energy Technology Data Exchange (ETDEWEB)

    Bucko, Juergen; Benzinger, Walther; Dittmeyer, Roland [Karlsruher Institut fuer Technologie (KIT), Eggenstein-Leopodshafen (Germany). Inst. fuer Mikroverfahrenstechnik (IMVT); Mayer, Moriz; Augustin, Wolfgang; Scholl, Stephan [Technische Univ. Braunschweig (Germany). Inst. fuer Chemische und Thermische Verfahrenstechnik (ICVT)

    2012-07-01

    The formation of fouling at heat transfer surfaces is a large problem in the operation of heat exchangers. Fouling impacts the thermal and fluid dynamic behaviour and may deteriorate the efficiency of heat exchangers. Systematic investigations on the fouling behaviour of micro-structured plants did not have taken place up to now. In view of the target distribution of micro-process engineering facilities, knowledge on the fouling behaviour of these facilities is very important. The authors of the contribution under consideration report on investigations of the fouling behaviour of calcium carbonate in micro channels with a cross-sectional area of 400 x 200 micron{sup 2}. The authors demonstrate the dependence of the crystallization fouling from the flow velocity, wall temperature and the ion concentration quantitatively. Furthermore, the fouling behaviour in micro-channels was visualized. The crystallization fouling has a significant impact on the thermal and fluid dynamic behaviour of the investigated micro-structured heat exchanger. The decrease of the performance of heat transfer may amount 50 % or more. Furthermore, the pressure loss may increase tenfold of the original process loss.

  10. Development of a multi-objective coagulation system for long-term fouling control in dead-end ultrafiltration

    NARCIS (Netherlands)

    Zondervan, Edwin; Blankert, Bastiaan; Betlem, Ben H.L.; Roffel, Brian

    2008-01-01

    In this paper, a multi-objective control system has been developed and experimentally tested. The multi-objective control system can be effectively used to control short-term fouling as well as long-term fouling. In an earlier study it was found that coagulant dosing in ultrafiltration can be used e

  11. Development of a multi-objective coagulation system for long-term fouling control in dead-end ultrafiltration

    NARCIS (Netherlands)

    Zondervan, Edwin; Blankert, Bastiaan; Betlem, Ben H. L.; Roffel, Brian

    2008-01-01

    In this paper, a multi-objective control system has been developed and experimentally tested. The multi-objective control system can be effectively used to control short-term fouling as well as long-term fouling. In an earlier Study it was found that coagulant dosing in ultrafiltration can be used e

  12. How different is the composition of the fouling layer of wastewater reuse and seawater desalination RO membranes?

    KAUST Repository

    Khan, Muhammad

    2014-08-01

    To study the effect of water quality and operating parameters on membrane fouling, a comparative analysis of wastewater (WW) and seawater (SW) fouled reverse osmosis (RO) membranes was conducted. Membranes were harvested from SWRO and WWRO pilot plants located in Vilaseca (East Spain), both using ultrafiltration as pretreatment. The SWRO unit was fed with Mediterranean seawater and the WWRO unit was operated using secondary effluent collected from the municipal wastewater treatment plant. Lead and terminal SWRO and WWRO modules were autopsied after five months and three months of operation, respectively. Ultrastructural, chemical, and microbiological analyses of the fouling layers were performed. Results showed that the WWRO train had mainly bio/organic fouling at the lead position element and inorganic fouling at terminal position element, whereas SWRO train had bio/organic fouling at both end position elements. In the case of WWRO membranes, Betaproteobacteria was the major colonizing species; while Ca, S, and P were the major present inorganic elements. The microbial population of SWRO membranes was mainly represented by Alpha and Gammaproteobacteria. Ca, Fe, and S were the main identified inorganic elements of the fouling layer of SWRO membranes. These results confirmed that the RO fouling layer composition is strongly impacted by the source water quality. © 2014 Elsevier Ltd.

  13. International Conference on Marine Corrosion and Fouling (5th), held 19-23 May 1980, Barcelona (Spain).

    Science.gov (United States)

    1980-12-31

    their breeding season at Lattakia Port." I A. Habal (Syria): "Fouling prevention of local Pinus brutia by shipworms, "limnoridii," and other marine... growth of fouling organisms at Alamedia marina, San Francisco Bay, California." E. Lindner (US): "Experiments in synthesis of barnacle adhesive." A

  14. How different is the composition of the fouling layer of wastewater reuse and seawater desalination RO membranes?

    Science.gov (United States)

    Khan, Muhammad Tariq; Busch, Markus; Molina, Veronica Garcia; Emwas, Abdul-Hamid; Aubry, Cyril; Croue, Jean-Philippe

    2014-08-01

    To study the effect of water quality and operating parameters on membrane fouling, a comparative analysis of wastewater (WW) and seawater (SW) fouled reverse osmosis (RO) membranes was conducted. Membranes were harvested from SWRO and WWRO pilot plants located in Vilaseca (East Spain), both using ultrafiltration as pretreatment. The SWRO unit was fed with Mediterranean seawater and the WWRO unit was operated using secondary effluent collected from the municipal wastewater treatment plant. Lead and terminal SWRO and WWRO modules were autopsied after five months and three months of operation, respectively. Ultrastructural, chemical, and microbiological analyses of the fouling layers were performed. Results showed that the WWRO train had mainly bio/organic fouling at the lead position element and inorganic fouling at terminal position element, whereas SWRO train had bio/organic fouling at both end position elements. In the case of WWRO membranes, Betaproteobacteria was the major colonizing species; while Ca, S, and P were the major present inorganic elements. The microbial population of SWRO membranes was mainly represented by Alpha and Gammaproteobacteria. Ca, Fe, and S were the main identified inorganic elements of the fouling layer of SWRO membranes. These results confirmed that the RO fouling layer composition is strongly impacted by the source water quality.

  15. Flux patterns and membrane fouling propensity during desalination of seawater by forward osmosis.

    Science.gov (United States)

    Li, Zhen-Yu; Yangali-Quintanilla, Victor; Valladares-Linares, Rodrigo; Li, Qingyu; Zhan, Tong; Amy, Gary

    2012-01-01

    The membrane fouling propensity of natural seawater during forward osmosis was studied. Seawater from the Red Sea was used as the feed in a forward osmosis process while a 2M sodium chloride solution was used as the draw solution. The process was conducted in a semi-batch mode under two crossflow velocities, 16.7 cm/s and 4.2 cm/s. For the first time reported, silica scaling was found to be the dominant inorganic fouling (scaling) on the surface of membrane active layer during seawater forward osmosis. Polymerization of dissolved silica was the major mechanism for the formation of silica scaling. After ten batches of seawater forward osmosis, the membrane surface was covered by a fouling layer of assorted polymerized silica clusters and natural organic matter, especially biopolymers. Moreover, the absorbed biopolymers also provided bacterial attachment sites. The accumulated organic fouling could be partially removed by water flushing while the polymerized silica was difficult to remove. The rate of flux decline was about 53% with a crossflow velocity of 16.7 cm/s while reaching more than 70% with a crossflow velocity of 4.2 cm/s. Both concentration polarization and fouling played roles in the decrease of flux. The salt rejection was stable at about 98% during seawater forward osmosis. In addition, an almost complete rejection of natural organic matter was attained. The results from this study are valuable for the design and development of a successful protocol for a pretreatment process before seawater forward osmosis and a cleaning method for fouled membranes.

  16. Flux patterns and membrane fouling propensity during desalination of seawater by forward osmosis

    KAUST Repository

    Li, Zhenyu

    2012-01-01

    The membrane fouling propensity of natural seawater during forward osmosis was studied. Seawater from the Red Sea was used as the feed in a forward osmosis process while a 2. M sodium chloride solution was used as the draw solution. The process was conducted in a semi-batch mode under two crossflow velocities, 16.7. cm/s and 4.2. cm/s. For the first time reported, silica scaling was found to be the dominant inorganic fouling (scaling) on the surface of membrane active layer during seawater forward osmosis. Polymerization of dissolved silica was the major mechanism for the formation of silica scaling. After ten batches of seawater forward osmosis, the membrane surface was covered by a fouling layer of assorted polymerized silica clusters and natural organic matter, especially biopolymers. Moreover, the absorbed biopolymers also provided bacterial attachment sites. The accumulated organic fouling could be partially removed by water flushing while the polymerized silica was difficult to remove. The rate of flux decline was about 53% with a crossflow velocity of 16.7. cm/s while reaching more than 70% with a crossflow velocity of 4.2. cm/s. Both concentration polarization and fouling played roles in the decrease of flux. The salt rejection was stable at about 98% during seawater forward osmosis. In addition, an almost complete rejection of natural organic matter was attained. The results from this study are valuable for the design and development of a successful protocol for a pretreatment process before seawater forward osmosis and a cleaning method for fouled membranes. © 2011 Elsevier Ltd.

  17. Effect of ferric and ferrous iron addition on phosphorus removal and fouling in submerged membrane bioreactors.

    Science.gov (United States)

    Zhang, Zhenghua; Wang, Yuan; Leslie, Greg L; Waite, T David

    2015-02-01

    The effect of continuously dosing membrane bioreactors (MBRs) with ferric chloride (Fe(III)) and ferrous sulphate (Fe(II)) on phosphorus (P) removal and membrane fouling is investigated here. Influent phosphorus concentrations of 10 mg/L were consistently reduced to effluent concentrations of less than 0.02 mg/L and 0.03-0.04 mg/L when an Fe(III)/P molar ratio of 4.0 and Fe/P molar ratio (for both Fe(II) and Fe(III)) of 2.0 were used, respectively. In comparison, effluent concentrations did not decrease below 1.35 mg/L in a control reactor to which iron was not added. The concentrations of supernatant organic compounds, particularly polysaccharides, were reduced significantly by iron addition. The sub-critical fouling time (tcrit) after which fouling becomes much more severe was substantially shorter with Fe(III) dosing (672 h) than with Fe(II) dosing (1200-1260 h) at Fe/P molar ratios of 2.0 while the control reactor (no iron dosing) exhibited a tcrit of 960 h. Not surprisingly, membrane fouling was substantially more severe at Fe/P ratios of 4. Fe(II) doses yielding Fe/P molar ratios of 2 or less with dosing to the aerobic chamber were found to be optimal in terms of P removal and fouling mitigation performance. In long term operation, however, the use of iron for maintaining appropriately low effluent P concentrations results in more severe irreversible fouling necessitating the application of an effective membrane cleaning regime.

  18. Fouling Behavior of Microstructured Hollow Fiber Membranes in Dead-End Filtrations: Critical Flux Determination and NMR Imaging of Particle Deposition

    NARCIS (Netherlands)

    Culfaz, P. Zeynep; Buetehorn, Steffen; Utiu, Lavinia; Kueppers, Markus; Bluemich, Bernhard; Melin, Thomas; Wessling, Matthias; Lammertink, Rob G.H.

    2011-01-01

    The fouling behavior of microstructured hollow fibers was investigated in constant flux filtrations of colloidal silica and sodium alginate. It was observed that the fouling resistance increases faster with structured fibers than with round fibers. Reversibility of structured fibers’ fouling was sim

  19. Thermodynamic analysis of effects of contact angle on interfacial interactions and its implications for membrane fouling control.

    Science.gov (United States)

    Chen, Jianrong; Shen, Liguo; Zhang, Meijia; Hong, Huachang; He, Yiming; Liao, Bao-Qiang; Lin, Hongjun

    2016-02-01

    Concept of hydrophobicity always fails to accurately assess the interfacial interaction and membrane fouling, which calls for reliable parameters for this purpose. In this study, effects of contact angle on interfacial interactions related to membrane fouling were investigated based on thermodynamic analysis. It was found that, total interaction energy between sludge foulants and membrane monotonically decreases and increases with water and glycerol contact angle, respectively, indicating that these two parameters can be reliable indicators predicting total interaction energy and membrane fouling. Membrane roughness decreases interaction strength for over 20 times, and effects of membrane roughness on membrane fouling should consider water and glycerol contact angle on membrane. It was revealed existence of a critical water and glycerol contact angle for a given membrane bioreactor. Meanwhile, diiodomethane contact angle has minor effect on the total interaction, and cannot be regarded as an effective indicator assessing interfacial interactions and membrane fouling.

  20. Fouling Characterization of Forward Osmosis Biomimetic Aquaporin Membranes Used for Water Recovery from Municipal Wastewater

    DEFF Research Database (Denmark)

    Zarebska, Agata; Petrinic, Irena; Hey, Tobias;

    /ultrafiltration coupled with RO and sand filtration, or advanced oxidation process require high energy. Contrary to pressure driven membrane processes, forward osmosis (FO) offers advantages such as no need of high hydraulic pressure, reduced fouling and simple cleaning. Even though fouling of FO membranes is less severe......Generally more than 99.93% of municipal wastewater is composed of water, therefore water recovery can alleviate global water stress which currently exists. Traditional ways to extract water from wastewater by the use of membrane bioreactors combined with reverse osmosis (RO), or micro...

  1. Polyamide desalination membrane characterization and surface modification to enhance fouling resistance.

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mukul M. (Univeristy of Texas at Austin, Austin, TX); Freeman, Benny D. (Univeristy of Texas at Austin, Austin, TX); Van Wagner, Elizabeth M. (Univeristy of Texas at Austin, Austin, TX); Hickner, Michael A. (Pennsylvania State University, University Park, PA); Altman, Susan Jeanne

    2010-08-01

    The market for polyamide desalination membranes is expected to continue to grow during the coming decades. Purification of alternative water sources will also be necessary to meet growing water demands. Purification of produced water, a byproduct of oil and gas production, is of interest due to its dual potential to provide water for beneficial use as well as to reduce wastewater disposal costs. However, current polyamide membranes are prone to fouling, which decreases water flux and shortens membrane lifetime. This research explored surface modification using poly(ethylene glycol) diglycidyl ether (PEGDE) to improve the fouling resistance of commercial polyamide membranes. Characterization of commercial polyamide membrane performance was a necessary first step before undertaking surface modification studies. Membrane performance was found to be sensitive to crossflow testing conditions. Concentration polarization and feed pH strongly influenced NaCl rejection, and the use of continuous feed filtration led to higher water flux and lower NaCl rejection than was observed for similar tests performed using unfiltered feed. Two commercial polyamide membranes, including one reverse osmosis and one nanofiltration membrane, were modified by grafting PEGDE to their surfaces. Two different PEG molecular weights (200 and 1000) and treatment concentrations (1% (w/w) and 15% (w/w)) were studied. Water flux decreased and NaCl rejection increased with PEGDE graft density ({micro}g/cm{sup 2}), although the largest changes were observed for low PEGDE graft densities. Surface properties including hydrophilicity, roughness and charge were minimally affected by surface modification. The fouling resistance of modified and unmodified membranes was compared in crossflow filtration studies using model foulant solutions consisting of either a charged surfactant or an oil in water emulsion containing n-decane and a charged surfactant. Several PEGDE-modified membranes demonstrated improved

  2. Research on Influence Factors of Membrane Fouling in A/O-MBR System

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the influence factors of membrane fouling in A/O-MBR system,so as to control membrane fouling better,prolong the service life of membrane,further reduce the cost of water treatment and promote the popularization of membrane bioreactor(MBR) effectively.[Method] Based on small A/O-MBR device,an orthogonal test with three factors(including aeration intensity,pump-stop ratio and mixed liquor suspended solid) and three levels was designed to optimize three parameters,and the effe...

  3. Linking biofilm growth to fouling and aeration performance of fine-pore diffuser in activated sludge.

    Science.gov (United States)

    Garrido-Baserba, Manel; Asvapathanagul, Pitiporn; McCarthy, Graham W; Gocke, Thomas E; Olson, Betty H; Park, Hee-Deung; Al-Omari, Ahmed; Murthy, Sudhir; Bott, Charles B; Wett, Bernhard; Smeraldi, Joshua D; Shaw, Andrew R; Rosso, Diego

    2016-03-01

    Aeration is commonly identified as the largest contributor to process energy needs in the treatment of wastewater and therefore garners significant focus in reducing energy use. Fine-pore diffusers are the most common aeration system in municipal wastewater treatment. These diffusers are subject to fouling and scaling, resulting in loss in transfer efficiency as biofilms form and change material properties producing larger bubbles, hindering mass transfer and contributing to increased plant energy costs. This research establishes a direct correlation and apparent mechanistic link between biofilm DNA concentration and reduced aeration efficiency caused by biofilm fouling. Although the connection between biofilm growth and fouling has been implicit in discussions of diffuser fouling for many years, this research provides measured quantitative connection between the extent of biofouling and reduced diffuser efficiency. This was clearly established by studying systematically the deterioration of aeration diffusers efficiency during a 1.5 year period, concurrently with the microbiological study of the biofilm fouling in order to understand the major factors contributing to diffuser fouling. The six different diffuser technologies analyzed in this paper included four different materials which were ethylene-propylene-diene monomer (EPDM), polyurethane, silicone and ceramic. While all diffusers foul eventually, some novel materials exhibited fouling resistance. The material type played a major role in determining the biofilm characteristics (i.e., growth rate, composition, and microbial density) which directly affected the rate and intensity at what the diffusers were fouled, whereas diffuser geometry exerted little influence. Overall, a high correlation between the increase in biofilm DNA and the decrease in αF was evident (CV aeration efficiency, the research was able to show quantitatively the causal connection between bacterial fouling and energy wastage during

  4. 膜生物反应器中膜污染机理研究%Investigation of Membrane Fouling Mechanisms in Membrane Bioreactors

    Institute of Scientific and Technical Information of China (English)

    刘雅娟; 赵建国

    2016-01-01

    Membrane bioreactor (MBR) is a combination system of a biological reactor and a membrane filtration module for munic⁃ipal and industrial wastewater treatment. The major obstacle for the wider practical application of MBR systems is membrane fouling which causes the rapid declination of permeate flux and low permeate quality. In order to find the best way to control the membrane fouling,this article reviews the factors influencing membrane fouling. It shows that membrane fouling is related to the physicochemical properties of membrane, such as material, pore size, hydrophobicity and surface charge, whereas it is also controlled by the characteris⁃tics of feed solutions, mixed liquor suspended solids concentration, morphology of sludge, surface charge, characteristics and composi⁃tion of supernatant and extracellular polymer substance,etc.%膜生物反应器(MBR)结合了生物反应器有效去除有机物和膜分离组件高出水水质的优点,广泛应用于处理各种生活污水和工业废水,限制MBR进一步推广应用的主要因素是膜污染。膜污染造成水通量急剧下降和出水水质变差。MBR中膜污染的形成机理复杂,不仅与膜材料、膜孔大小、膜的疏水性和表面电荷等物理化学特性相关,而且和废水、污泥和上清液的特性有密切的关系。本综述从混合液悬浮固体浓度、污泥结构特点、上清液特征和组成成分及胞外聚合物等几方面对造成膜污染现象的机理进行分析总结,以找到制约和减少膜污染发生的具体方向。

  5. Effects of pharmaceutical micropollutants on the membrane fouling of a submerged MBR treating municipal wastewater: case of continuous pollution by carbamazepine.

    Science.gov (United States)

    Li, Chengcheng; Cabassud, Corinne; Reboul, Bernard; Guigui, Christelle

    2015-02-01

    Membrane bioreactor (MBR) is increasingly used for municipal wastewater treatment and reuse and great concerns have been raised to some emerging trace pollutants found in aquatic environment in the last decade, notably the pharmaceuticals. As a consequence the removal of pharmaceutical micropollutants by MBRs has been extensively investigated. But there is still a lack of knowledge on the effects of the current presence of pharmaceutical micropollutants in domestic wastewaters on MBR fouling. Among the different pharmaceuticals, it was decided to focus on carbamazepine (CBZ), an anti-epileptic drug, because of its occurrence in domestic wastewaters and persistency in biological processes including MBRs. This paper focuses on the effects of continuous carbamazepine pollution on MBR fouling. A continuous introduction of CBZ into the MBR via the feed (about 90 μg L(-1) CBZ in the feed) provoked a TMP jump. It occurred just 1 day after the addition of CBZ in MBR and a significantly higher increase rate of TMP was also observed after 1 day after addition of CBZ in MBR, as compared to that before addition of CBZ. This indicates that the pharmaceutical stress induced by CBZ causes more severe membrane fouling. Addition of CBZ was shown to induce a significant increase of the concentration of proteins in the supernatant at the beginning several days then stabilized to original level whereas no significant change was found for polysaccharides. HPLC-SEC analysis showed that addition of CBZ induced a decrease of 100-1000 kDa protein-like SMPs and a more significant increase of 10-100 kDa protein-like SMPs in the supernatant. Moreover it was found that addition of CBZ in the MBR affected the sludge microbial activities, as a slight inhibition (about 20%) of the exogenous respiration rate was observed. The increased membrane fouling could be related to the change in biomass characteristics and supernatant quality after addition of CBZ in MBR. This study allows also

  6. Toxicity of anti-fouling paints for use on ships and leisure boats to non-target organisms representing three trophic levels

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Jenny [Department of Applied Environmental Science (ITM), Stockholm University, SE-106 91 Stockholm (Sweden); Ytreberg, Erik, E-mail: erik.ytreberg@itm.su.s [Department of Applied Environmental Science (ITM), Stockholm University, SE-106 91 Stockholm (Sweden); Eklund, Britta [Department of Applied Environmental Science (ITM), Stockholm University, SE-106 91 Stockholm (Sweden)

    2010-03-15

    Leachates of anti-fouling paints for use on ships and leisure boats are examined for their ecotoxicological potential. Paint leachates were produced in both 7 per mille artificial (ASW) and natural seawater (NSW) and tested on three organisms, the bacterium Vibrio fischeri, the macroalga Ceramium tenuicorne, and the crustacean Nitocra spinipes. Generally, leaching in ASW produced a more toxic leachate and was up to 12 times more toxic to the organisms than was the corresponding NSW leachate. The toxicity could be explained by elevated concentrations of Cu and Zn in the ASW leachates. Of the NSW leachates, those from the ship paints were more toxic than those from leisure boat paints. The most toxic paint was the biocide-free leisure boat paint Micron Eco. This implies that substances other than added active agents (biocides) were responsible for the observed toxicity, which would not have been discovered without the use of biological tests. - Leachate from a biocide-free anti-fouling paint for leisure boat use was more toxic than leachates from ship paints.

  7. 海洋污损生物防除方法概述及发展趋势%Antifouling Method of Marine Fouling Organisms--A Review

    Institute of Scientific and Technical Information of China (English)

    胥震; 欧阳清; 易定和

    2012-01-01

    海洋污损生物对船舶等海洋结构物的污损已经成为人类从事海洋开发活动的一大障碍.本文综述了污损生物附着机理及其危害,介绍了当前工程应用和研究中的主要防污损技术:物理防污法、化学防污法和生物防污法.分析了各类防污方法的防污机理及优缺点,展望了防污技术未来的研究和发展趋势.%The fouling organism accreted to marine installations is a major factor affecting their safety and service life. The tarnish of marine fouling organism to marine structures such as ships has become tremendous impediment to human activity in ocean. This article summarizes the adhesion mechanism and scathes of marine organism. Besides, the main antifouling methods at present, which classified as physical method, chemical method and biological method, are analyzed in term of antifouling mechanism, relative merits and so on. Finally, the future trends of antifouling methods research and development have been suggested.

  8. Fouling control mechanisms of demineralized water backwash: Reduction of charge screening and calcium bridging effects

    KAUST Repository

    Li, Sheng

    2011-12-01

    This paper investigates the impact of the ionic environment on the charge of colloidal natural organic matter (NOM) and ultrafiltration (UF) membranes (charge screening effect) and the calcium adsorption/bridging on new and fouled membranes (calcium bridging effect) by measuring the zeta potentials of membranes and colloidal NOM. Fouling experiments were conducted with natural water to determine whether the reduction of the charge screening effect and/or calcium bridging effect by backwashing with demineralized water can explain the observed reduction in fouling. Results show that the charge of both membranes and NOM, as measured by the zeta potential, became more negative at a lower pH and a lower concentration of electrolytes, in particular, divalent electrolytes. In addition, calcium also adsorbed onto the membranes, and consequently bridged colloidal NOM and membranes via binding with functional groups. The charge screening effect could be eliminated by flushing NOM and membranes with demineralized water, since a cation-free environment was established. However, only a limited amount of the calcium bridging connection was removed with demineralized water backwashes, so the calcium bridging effect mostly could not be eliminated. As demineralized water backwash was found to be effective in fouling control, it can be concluded that the reduction of the charge screening is the dominant mechanism for this. © 2011 Elsevier Ltd.

  9. Fouling and long-term durability of an integrated forward osmosis and membrane distillation system.

    Science.gov (United States)

    Husnain, T; Mi, B; Riffat, R

    2015-01-01

    An integrated forward osmosis (FO) and membrane distillation (MD) system has great potential for sustainable wastewater reuse. However, the fouling and long-term durability of the system remains largely unknown. This study investigates the fouling behaviour and efficiency of cleaning procedures of FO and MD membranes used for treating domestic wastewater. Results showed that a significant decline in flux of both FO and MD membranes were observed during treatment of wastewater with organic foulants. However, shear force generated by the increased cross-flow physically removed the loosely attached foulants from the FO membrane surface and resulted in 86-88% recovery of flux by cleaning with tap water. For the MD membrane, almost no flux recovery was achieved due to adsorption of organic foulants on the hydrophobic membrane surface, thus indicating significant irreversible fouling/wetting, which may not be effectively cleaned even with chemical reagents. Long-term (10 d) tests showed consistent performance of the FO membrane by rejecting the contaminants. However, organic foulants reduced the hydrophobicity of the MD membrane, caused wetting problems and allowed contaminants to pass through. The results demonstrate that combination of the FO and MD processes can effectively reduce irreversible membrane fouling and solve the wetting problem of the MD membrane.

  10. [DOM membrane fouling and effects on rejection behaviors of NF membranes].

    Science.gov (United States)

    Feng, Gui-Zhen; Dong, Bing-Zhi

    2013-11-01

    This work investigated membrane fouling caused by two kinds of dissolved organic matters (DOMs), i. e., Qingcaosha (QCS) DOM and Taihu lake (TH) DOM, and the effects on the rejection behaviors of two different nanofiltration (NF) membranes, i. e., HL and ESNA1-K, using carbamazepine (CBZ) as a molecular indicator. The results showed that severe membrane fouling occurred in the presence of DOM. And the CBZ removal rate was associated with the properties and characteristics of the organic matters and the membranes. It was found that the hydrophobicity of adhered DOM cake layer was responsible for the flux decline and the influence of CBZ removal. QCS DOM increased the retention of CBZ, while TH DOM decreased the rejection rate of CBZ by both membranes tested. DOMs at medium relative molecular weight (M(r) 1 500-10 000) could adhere closely to NF membranes to form cake layer, thus changed the hydrophobicity of the membranes. DOMs at low molecular weight could enter the membrane pores reducing the M(r), which influenced the CBZ removal and resulted in membrane fouling. The experiment also showed that DOM of TH contained more hydrophobic organic matters than that of QCS, the adhesion free energy and cohesion free energy of which was more negative, and the resulting membrane fouling and membrane flux decline were more severe.

  11. Integrated approach to characterize fouling on a flat sheet membrane gravity driven submerged membrane bioreactor.

    Science.gov (United States)

    Fortunato, Luca; Jeong, Sanghyun; Wang, Yiran; Behzad, Ali R; Leiknes, TorOve

    2016-12-01

    Fouling in membrane bioreactors (MBR) is acknowledged to be complex and unclear. An integrated characterization methodology was employed in this study to understand the fouling on a gravity-driven submerged MBR (GD-SMBR). It involved the use of different analytical tools, including optical coherence tomography (OCT), liquid chromatography with organic carbon detection (LC-OCD), total organic carbon (TOC), flow cytometer (FCM), adenosine triphosphate analysis (ATP) and scanning electron microscopy (SEM). The three-dimensional (3D) biomass morphology was acquired in a real-time through non-destructive and in situ OCT scanning of 75% of the total membrane surface directly in the tank. Results showed that the biomass layer was homogeneously distributed on the membrane surface. The amount of biomass was selectively linked with final destructive autopsy techniques. The LC-OCD analysis indicated the abundance of low molecular weight (LMW) organics in the fouling composition. Three different SEM techniques were applied to investigate the detailed fouling morphology on the membrane.

  12. Effect of sludge retention time on sludge characteristics and membrane fouling of membrane bioreactor

    Institute of Scientific and Technical Information of China (English)

    OUYANG Ke; LIU Junxin

    2009-01-01

    Three identical membrane bioreactors (MBRs) were operated over 2 years at different sludge retention times (SRT) of 10, 40 d and no sludge withdrawal (NS), respectively, to elucidate and quantify the effect of SRT on the sludge characteristics and membrane fouling. The hydraulic retention times of these MBRs were controlled at 12 h. With increasing SRT, the sludge concentrations in the MBRs increased, whereas the ratio of volatile suspended solid to the total solid decreased, and the size of sludge granule diminished in the meantime. A higher sludge concentration at long SRT could maintain a better organic removal efficiency, and a longer SRT was propitious to the growth of nitrifiers. The performance of these MBRs for the removal of COD and NH4+-N did not change much with different SRTs. However, the bioactivity decreased as SRT increased. The measurements of specific oxygen uptake rates (SOUR) and fluorescence in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes testified that SOUR and the proportion of the bacteria-specific probe EUB338 in all DAPI-stainable bacteria decreased with increasing SRT. The concentrations of total organic carbon, protein, polysaccharides and soluble extracellular polymeric substance (EPS) in the mixed liquor supernatant decreased too with increasing SRT. The membrane fouling rate was higher at shorter SRT, and the highest fouling rate appeared at a SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the relative contribution of the gel layer decreased as SRT increased.

  13. Denaturation Kinetics of Whey Protein Isolate Solutions and Fouling Mass Distribution in a Plate Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Marwa Khaldi

    2015-01-01

    Full Text Available Few investigations have attempted to connect the mechanism of dairy fouling to the chemical reaction of denaturation (unfolding and aggregation occurring in the bulk. The objective of this study is to contribute to this aspect in order to propose innovative controls to limit fouling deposit formation. Experimental investigations have been carried out to observe the relationship between the deposit mass distribution generated in plate heat exchangers (PHE by a whey protein isolate (WPI mainly composed of β-lactoglobulin (β-Lg and the ratio between the unfolding and aggregation rate constants. Experiments using a PHE were carried out at a pilot scale to identify the deposit distribution of a model fouling solution with different calcium contents. In parallel, laboratory experiments were performed to determine the unfolding/aggregation rate constants. Data analysis showed that (i β-Lg denaturation is highly dependent on the calcium content, (ii for each fouling solution, irrespective of the imposed temperature profile, the deposit mass in each channel and the ratio between the unfolding and aggregation rate constants seem to be well correlated. This study demonstrates that both the knowledge of the thermal profile and the β-Lg denaturation rate constants are required in order to predict accurately the deposit distribution along the PHE.

  14. FOULING PREVENTION WITH FLUIDIZED PARTICLES IN EVAPORATION OF TRADITIONAL CHINESE MEDICINE EXTRACT

    Institute of Scientific and Technical Information of China (English)

    Mingyan Liu; Xiulun Li; Ruitai Lin; Wanda Nie; Rucheng Zhang; Ningsheng Ling

    2004-01-01

    The present investigation shows that comparing with the evaporation of vapor-liquid two-phase flow boiling system, heat transfer is enhanced by adding proper inert solid particles into the traditional Chinese medicine liquid which is under evaporation. As a result, fouling prevention effects are evident in such three-phase flow boiling evaporator.

  15. NOM and TEP fouling of a forward osmosis (FO) membrane: Foulant identification and cleaning

    KAUST Repository

    Valladares Linares, Rodrigo

    2012-12-01

    The study of forward osmosis (FO) membranes has increased due to the already demonstrated advantages compared to high-energy membrane processes such as reverse osmosis (RO). This research focuses on characterization of the natural organic matter (NOM) fraction causing fouling on the active layer (AL) of a FO membrane in a novel plate and frame module configuration, facing secondary wastewater effluent as a feed solution (FS) and seawater used as a draw solution (DS). In addition, transparent exopolymer particles (TEP) were observed on the support layer (SL) of the membrane in contact with the DS. The NOM fouling layer, after characterizing the water samples and membranes used, was found to be composed of biopolymers and protein-like substances, which adversely affect the flux of water through the FO membrane. However, NOM fouling showed high reversibility, up to 90% when air scouring for 15. min is used as a cleaning technique. The irreversible fouling in this work was found to be 8.2% after chemical cleaning. On the support layer of the membrane, TEP formed clusters clearly identifiable with an optical microscope and a TEP-specific dye. Chemical cleaning with 1% NaOCl for 10. min proved to be the most effective method to remove TEP. © 2012.

  16. Cross-linked polystyrene sulfonic acid and polyethylene glycol as a low-fouling material.

    Science.gov (United States)

    Alghunaim, Abdullah; Zhang Newby, Bi-min

    2016-04-01

    A negatively charged hydrophilic low fouling film was prepared by thermally cross-linking a blend consisting of polystyrene sulfonic acid (PSS) and polyethylene glycol (PEG). The film was found to be stable by dip-washing. The fouling resistance of this material toward bacterial (Escherichia coli) and colloidal (polystyrene particles) attachment, non-specific protein (fibronectin) adsorption and cell (3T3 NIH) adhesion was evaluated and was compared with glass slides modified with polyethylene glycol (PEG) brushes, oxidized 3-mercaptopropyltrimethoxysilane (sulfonic acid, SA), and n-octadecyltrichlorosilane (OTS). The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and thermodynamic models based on surface energy were used to explain the interaction behaviors of E. coli/polystyrene particles-substrate and protein-substrate interactions, respectively. The cross-linked PSS-PEG film was found to be slightly better than SA and PEG toward resisting non-specific protein adsorption, and showed comparable low attachment results as those of PEG toward particle, bacterial and NIH-3T3 cells adhesion. The low-fouling performance of PSS-PEG, a cross-linked film by a simple thermal curing process, could allow this material to be used for applications in aqueous environments, where most low fouling hydrophilic polymers, such as PSS or PEG, could not be easily retained.

  17. Membrane Fouling Potential of Secondary Effluent Organic Matter (EfOM) from Conventional Activated Sludge Process

    KAUST Repository

    Wei, Chunhai

    2012-01-01

    Secondary effluent organic matter (EfOM) from a conventional activated sludge process was filtered through constant-pressure dead-end filtration tests with a sequential ultrafiltration (UF, molecular weight cut-off (MWCO) of 10k Dalton) and nanofiltration (NF, MWCO of 200 Dalton) array to investigate its membrane fouling potential. Advanced analytical methods including liquid chromatography with online carbon detection (LC-OCD) and fluorescent excitation-emission matrix (F-EEM) were employed for EfOM characterization. EfOM consisted of humic substances and building blocks, low molecular weight (LMW) neutrals, biopolymers (mainly proteins) and hydrophobic organics according to the sequence of their organic carbon fractions. The UF rejected only biopolymers and the NF rejected most humics and building blocks and a significant part of LMW neutrals. Simultaneous occurrence of cake layer and standard blocking during the filtration process of both UF and NF was identified according to constant-pressure filtration equations, which was possibly caused by the heterogeneous nature of EfOM with a wide MW distribution (several ten to several million Dalton). Thus the corresponding two fouling indices (kc for cake layer and ks for standard blocking) from UF and NF could characterize the fouling potential of macromolecular biopolymers and low to intermediate MW organics (including humics, building blocks, LMW neutrals), respectively. Compared with macromolecular biopolymers, low to intermediate MW organics exhibited a much higher fouling potential due to their lower molecular weight and higher concentration.

  18. The effects of copper pollution on fouling assemblage diversity: a tropical-temperate comparison.

    Directory of Open Access Journals (Sweden)

    João Canning-Clode

    Full Text Available BACKGROUND: The invasion of habitats by non-indigenous species (NIS occurs at a global scale and can generate significant ecological, evolutionary, economic and social consequences. Estuarine and coastal ecosystems are particularly vulnerable to pollution from numerous sources due to years of human-induced degradation and shipping. Pollution is considered as a class of disturbance with anthropogenic roots and recent studies have concluded that high frequencies of disturbance may facilitate invasions by increasing the availability of resources. METHODOLOGY/PRINCIPAL FINDINGS: To examine the effects of heavy metal pollution as disturbance in shaping patterns of exotic versus native diversity in marine fouling communities we exposed fouling communities to different concentrations of copper in one temperate (Virginia and one tropical (Panama region. Diversity was categorized as total, native and non-indigenous and we also incorporated taxonomic and functional richness. Our findings indicate that total fouling diversity decreased with increasing copper pollution, whether taxonomic or functional diversity is considered. Both native and non-indigenous richness decreased with increasing copper concentrations at the tropical site whereas at the temperate site, non-indigenous richness was too low to detect any effect. CONCLUSIONS/SIGNIFICANCE: Non-indigenous richness decreased with increasing metal concentrations, contradicting previous investigations that evaluate the influence of heavy metal pollution on diversity and invasibility of fouling assemblages. These results provide first insights on how the invasive species pool in a certain region may play a key role in the disturbance vs. non-indigenous diversity relationship.

  19. Airfoil-shaped micro-mixers for reducing fouling on membrane surfaces

    Science.gov (United States)

    Ho, Clifford K; Altman, Susan J; Clem, Paul G; Hibbs, Michael; Cook, Adam W

    2012-10-23

    An array of airfoil-shaped micro-mixers that enhances fluid mixing within permeable membrane channels, such as used in reverse-osmosis filtration units, while minimizing additional pressure drop. The enhanced mixing reduces fouling of the membrane surfaces. The airfoil-shaped micro-mixer can also be coated with or comprised of biofouling-resistant (biocidal/germicidal) ingredients.

  20. Integrated approach to characterize fouling on a flat sheet membrane gravity driven submerged membrane bioreactor

    KAUST Repository

    Fortunato, Luca

    2016-10-07

    Fouling in membrane bioreactors (MBR) is acknowledged to be complex and unclear. An integrated characterization methodology was employed in this study to understand the fouling on a gravity-driven submerged MBR (GD-SMBR). It involved the use of different analytical tools, including optical coherence tomography (OCT), liquid chromatography with organic carbon detection (LC-OCD), total organic carbon (TOC), flow cytometer (FCM), adenosine triphosphate analysis (ATP) and scanning electron microscopy (SEM). The three-dimensional (3D) biomass morphology was acquired in a real-time through non-destructive and in situ OCT scanning of 75% of the total membrane surface directly in the tank. Results showed that the biomass layer was homogeneously distributed on the membrane surface. The amount of biomass was selectively linked with final destructive autopsy techniques. The LC-OCD analysis indicated the abundance of low molecular weight (LMW) organics in the fouling composition. Three different SEM techniques were applied to investigate the detailed fouling morphology on the membrane. © 2016 Elsevier Ltd

  1. Assessment of silt density index (SDI) as fouling propensity parameter in reverse osmosis (RO) desalination systems

    KAUST Repository

    Rachman, Rinaldi

    2013-01-01

    Due to its simplicity, silt density index (SDI) is extensively used in reverse osmosis systems despite its limitations in predicting membrane fouling. Employing a reliable fouling index with good reproducibility and precision is necessary. The aim of this investigation is to assess the reliability of SDI in order to understand the reasons for the low level of precision and accuracy. Different commercial SDI membranes and feed water quality were used in this study. Results showed the existence of membrane properties\\' variation within manufacturers, which then causes a lack of accuracy in fouling risk estimation. The nature of particles during SDI filtration provides information that particle concentration and size play a significant role in SDI quantification with substantial representation given by particles with size close to membrane nominal pore size. Moreover, turbidity-assisted SDI measurements along with determination of ultrafiltration permeate and clean water fouling potential, establish the indication of nonfouling-related phenomena involved on SDI measurement such as natural organic matter adsorption and hydrodynamic conditions that alters during filtration. Additionally, it was found that the latter affects the sensitivity of SDI by being represented by some portions of SDI values. © 2013 Desalination Publications.

  2. Prediction of membrane fouling in MBR systems using empirically estimated specific cake resistance.

    Science.gov (United States)

    Khan, S Jamal; Visvanathan, C; Jegatheesan, V

    2009-12-01

    The focus of this study was to empirically estimate the specific cake resistance (SCR) by the variation in shear intensity (G) in four laboratory-scale MBRs. The control reactor (MBR(0)) was operated with aeration only while other MBRs (MBR(150), MBR(300) and MBR(450)) were operated with aeration and mechanical mixing intensities of 150, 300 and 450 rpm, respectively. It was found that the SCR was strongly correlated (R(2)=0.99) with the fouling rates in the MBRs. Moreover, the contribution of cake resistance (R(c)) to the total hydraulic resistance (R(t)) was predominant compared to the irreversible fouling resistance (R(f)). On this basis, the cake filtration model was selected as a predictive tool for membrane fouling. This model was modified by replacing the SCR with its empirical shear intensity relationship. The modified model can predict the fouling rate for a given shear intensity (G) within 80 and 250 s(-1) in a MBR system.

  3. Characterization of soluble microbial products and their fouling impacts in membrane bioreactors

    KAUST Repository

    Jiang, Tao

    2010-09-01

    Membrane bioreactor (MBR) fouling is not only influenced by the soluble microbial products (SMP) concentration but by their characteristics. Experiments of separate producing biomass associated products (BAP) and utilization associated products (UAP) allowed the separation of BAP and UAP effects from sludge water (SW). Thus, filtration of individual SMP components and further characterization becomes possible. Unstirred cell filtration was used to study fouling mechanisms and liquid chromatography-organic carbon detection (LC-OCD) and fluorescence excitation-emission matrix (EEM) were used to characterize the foulant. Generally, the SMP exhibiting characteristics of higher molecular weight, greater hydrophilicity and a more reduced state showed a higher retention percentage. However, the higher retention does not always yield higher fouling effects. The UAP filtration showed the highest specific cake resistance and pore blocking resistance attributed to their higher percentage of low molecular weight molecules, although their retention percentage was lower than the SW and BAP filtration. The UAP produced in the cell proliferation phase appeared to have the highest fouling potential. © 2010 American Chemical Society.

  4. Superheater fouling in a BFB boiler firing wood-based fuel blends

    NARCIS (Netherlands)

    Stam, A.F.; Haasnoot, K.; Brem, G.

    2014-01-01

    Four different fuel blends have been fired in a 28 MWel BFB. Wood pellets (test 0) were not problematic for about ten years, contrary to a mixture of demolition wood, wood cuttings, compost overflow, paper sludge and roadside grass (test 1) which caused excessive fouling at a superheater bundle afte

  5. Using SDI, SDI+ and MFI to evaluate fouling in a UR/RO desalination pilot plant

    NARCIS (Netherlands)

    Al-Hadidi, A.M.M.; Kemperman, A.J.B.; Schurer, H.; Schippers, J.C.; Wessling, M.; Meer, van der W.G.J.

    2012-01-01

    This paper assesses the performance of a UF/RO demonstration plant located in the Oosterschelde estuary in the south-western part of the Netherlands. Spring blooms in the seawater pose a challenge to the plant because of the resulting increased fouling potential of the water. Determinations of the f

  6. [Effect of Membrane Wettability on Membrane Fouling and Chemical Durability of SPG Membranes].

    Science.gov (United States)

    Zhang, Jing; Xiao, Tai-min; Zhang, Jing; Cao, Li-ya; Du, Ya-wei; Liu, Chun; Zhang, Lei

    2015-05-01

    Shirasu porous glass (SPG) membranes have been applied for microbubble aeration in aerobic wastewater treatment. In the present study, both hydrophilic and hydrophobic SPG membranes were used in a microbubble-aerated biofilm reactor with online chemical cleaning, and their membrane fouling and chemical durability were determined to be strongly dependent on the membrane wettability. The fouling layer formed on the surface of both membranes was confirmed to be mainly organic fouling, and the hydrophobic membrane showed a relatively stronger resistance to the organic fouling. The severe chemical corrosion of the hydrophilic membrane was observed due to exposure to the alkaline sodium hypochlorite solution used for chemical cleaning, which resulted in significant increases in the median pore diameter and the porosity. On the other hand, the pore structure of the hydrophobic membrane changed slightly when exposed to the alkaline sodium hypochlorite solution, suggesting its strong alkali-resistance due to the non-wetting surface. However, the surface hydrophobic groups of hydrophobic membrane could be oxidized by sodium hypochlorite solution, resulting in more wettable membrane surface. The hydrophobic membrane also showed better performance in the respects of oxygen transfer, contaminant removal and energy-saving. Therefore, the hydrophobic membrane seemed more appropriate to be applied for microbubble aeration in aerobic wastewater treatment process.

  7. Effect of fouling on removal of trace organic compounds by nanofiltration

    NARCIS (Netherlands)

    Hajibabania, S.; Verliefde, A.R.D.; Drewes, J.E.; Nghiem, L.D.; McDonald, J.; Khan, S.; Le-Clech, P.

    2011-01-01

    The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic cont

  8. Inefficacy of osmotic backwash induced by sodium chloride salt solution in controlling SWRO membrane fouling

    Science.gov (United States)

    Farooque, A. Mohammed; Al-Jeshi, Subhi; Saeed, Mohamed O.; Alreweli, Ali

    2014-12-01

    A study was conducted to evaluate the efficacy of osmotic backwash induced by high salt (NaCl) concentration solution on feed side of seawater reverse osmosis (SWRO) membranes, online and offline, in controlling membrane fouling and therefore minimizing/eliminating the need for chemical cleaning. SWRO membranes were deliberately fouled by feeding seawater from an open intake located on the Arabian Gulf Coast without dosing chemicals. The fouled membranes were subjected to offline cleaning with the salt solution of up to 25 % concentration. Despite the partial removal of foulants from the membrane surface, SWRO membrane performance could not be restored, indicating the ineffectiveness of osmotic backwash in aiding offline salt cleaning. Similarly, online osmotic backwash was found to be not only ineffective in removing foulants from membrane surfaces but actually increased the fouling rate, as indicated by faster fouling rates compared to other cases. Although the driving force required for the osmotic backwash existed, the generated back flow proved to be insufficient to detach foulants from membrane surfaces. During the study period, the average SWRO membrane flux was maintained between 19 and 23 LMH, whereas the average generated back flow flux by high salt concentration solution was only 11 LMH, which was not adequate to remove foulants from membrane surfaces. Moreover, it seems that the membrane configuration as well as inherent microstructure of SWRO membrane places certain constraints on the osmotic backwash process and renders osmotic backwash ineffective in tackling SWRO membrane fouling. Hence, chemical cleaning is essential to restore SWRO membrane performance whenever fouling occurs, and the use of highly concentrated salt solution does not have any significant benefit. Membrane autopsy revealed only an insignificant accumulation of biofouling layer despite the absence of disinfection. However, it was shown that culturable biofilm bacteria species

  9. Model for seawater fouling and effects of temperature, flow velocity and surface free energy on seawater fouling☆

    Institute of Scientific and Technical Information of China (English)

    Dazhang Yang; Jianhua Liu; Xiaoxue E; Linlin Jiang

    2016-01-01

    A kinetic model was proposed to predict the seawater fouling process in the seawater heat exchangers. The new model adopted an expression combining depositional and removal behaviors for seawater fouling based on the Kern–Seaton model. The present model parameters include the integrated kinetic rate of deposition (kd) and the integrated kinetic rate of removal (kr), which have clear physical significance. A seawater-fouling monitoring de-vice was established to validate the model. The experimental data were wel fitted to the model, and the param-eters were obtained in different conditions. SEM and EDX analyses were performed after the experiments, and the results show that the main components of seawater fouling are magnesium hydroxide and aluminum hy-droxide. The effects of surface temperature, flow velocity and surface free energy were assessed by the model and the experimental data. The results indicate that the seawater fouling becomes aggravated as the surface tem-perature increased in a certain range, and the seawater fouling resistance reduced as the flow velocity of seawater increased. Furthermore, the effect of the surface free energy of metals was analyzed, showing that the lower sur-face free energy mitigates the seawater fouling accumulation.

  10. INVESTIGATION OF FOULING DEPOSIT FORMATION DURING PASTEURIZATION OF CHILI SAUCE BY USING LAB-SCALE CONCENTRIC TUBE-PASTEURIZER

    Directory of Open Access Journals (Sweden)

    NUR ATIKA ALI

    2014-06-01

    Full Text Available This paper investigates the characteristics of fouling deposits obtained from chilli sauce pasteurization. A lab-scale concentric tube-pasteurizer was used to pasteurize the chilli sauce at 0.712 kg/min and 90±5°C. It was operated for 3 hours. Temperature changes were recorded during pasteurization and the data was used to plot the heat transfer profile and the fouling resistance profile. The thickness of the fouling deposit was also measured and the image was taken for every hour. The fouling deposit was collected at every hour to test its stickiness, hardness and flow behaviour. Proximate analysis was also performed and it shows that the fouling deposit from the chilli sauce is categorized as carbohydrate-based fouling deposits. Activation energy of chilli sauce is 7049.4 J.mole-1 which shows a greater effect of temperature on the viscosity. The hardness, stickiness of fouling deposit and the heat resistance increases as the chilli sauce continuously flows inside the heat exchanger.

  11. Hydrophilic Fe2O3 dynamic membrane mitigating fouling of support ceramic membrane in ultrafiltration of oil/water emulsion

    KAUST Repository

    Lu, Dongwei

    2016-03-17

    Oil/water (O/W) emulsion is daily produced and difficult to be treated effectively. Ceramic membrane ultrafiltration is one of reliable processes for the treatment of O/W emulsion, yet still hindered by membrane fouling. In this study, two types of Fe2O3 dynamic membranes (i.e., pre-coated dynamic membrane and self-forming dynamic membrane) were prepared to mitigate the fouling of support ceramic membrane in O/W emulsion treatment. Pre-coated dynamic membrane (DM) significantly reduced the fouling of ceramic membrane (i.e., 10% increase of flux recovery rate), while self-forming dynamic membrane aggravated ceramic membrane fouling (i.e., 8.6% decrease of flux recovery rate) after four filtration cycles. A possible fouling mechanism was proposed to explain this phenomenon, which was then confirmed by optical images of fouled membranes and the analysis of COD rejection. In addition, the cleaning efficiency of composite membranes (i.e., Fe2O3 dynamic membrane and support ceramic membrane) was enhanced by substitution of alkalescent water backwash for deionized water backwash. The possible reason for this enhancement was also explained. Our result suggests that pre-coated Fe2O3 dynamic membrane with alkalescent water backwash can be a promising technology to reduce the fouling of ceramic membrane and enhance membrane cleaning efficiency in the treatment of oily wastewater.

  12. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: Roles played by stabilization surfactants of oil droplets

    KAUST Repository

    Lu, Dongwei

    2015-04-07

    Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater. © 2015 American Chemical Society.

  13. Effect of silica fouling on the removal of pharmaceuticals and personal care products by nanofiltration and reverse osmosis membranes.

    Science.gov (United States)

    Lin, Yi-Li; Chiou, Jheng-Hong; Lee, Chung-Hsiang

    2014-07-30

    In this study, one reverse osmosis (XLE) and two nanofiltration (NF90 and NF270) membranes were fouled by silica to evaluate its effect on the flux decline as well as the removal of six pharmaceuticals and personal care products (PPCPs) including carbamazapine (CBZ), triclosan (TRI), ibuprofen (IBU), sulfadiazine (DIA), sulfamethoxazole (SMX) and sulfamethazine (SMZ) from pH 3 to 10. The membranes were characterized by physicochemical properties including hydrophobicity, surface morphology and PPCPs adsorption with or without the presence of silica fouling to validate the rejection mechanisms of PPCPs. The fouling mechanisms were investigated using the modified Hermia model. It was found that all membranes with silica fouling showed more severe permeate flux decline at low pHs (3 and 5) than at high pHs (8 and 10) by the decomposition of nonionized silica particles to form a dense gel layer on membrane surfaces, which was hard to be removed by backwash. Silica fouling rendered the membrane surface considerably more hydrophilic, and only IBU, TRI and SMZ were adsorbed on membranes. Silica fouling on tight membranes (NF90 and XLE) can promote rejection of most PPCPs because the dense fouling layer could supply membrane with synergistic steric hindrance to reduce the transportation of PPCPs across membrane surface, implying that size exclusion is the dominating mechanism. While for loose NF270, electrostatic repulsion dominates by enhanced rejection of PPCPs as pH increased. Although fouling layer could provide extra steric hindrance for NF270, its effect was overwhelmed by the accompanied cake-enhanced concentration polarization phenomenon (CEOP). CEOP impeded back diffusion of PPCPs into the feed solution, trapped and accumulated PPCPs on membrane surface so as to increase their diffusion across membrane. At all pH levels, intermediate blocking and gel layer formation was the major fouling mechanism for tight and loose membrane, respectively.

  14. Membrane fouling and wetting in membrane distillation and their mitigation by novel membranes with special wettability.

    Science.gov (United States)

    Wang, Zhangxin; Lin, Shihong

    2017-04-01

    Membrane distillation (MD) has been identified as a promising technology to desalinate the hypersaline wastewaters from fracking and other industries. However, conventional hydrophobic MD membranes are highly susceptible to fouling and/or wetting by the hydrophobic and/or amphiphilic constituents in these wastewaters of complex compositions. This study systematically investigates the impact of the surface wetting properties on the membrane wetting and/or fouling behaviors in MD. Specifically, we compare the wetting and fouling resistance of three types of membranes of different wetting properties, including hydrophobic and omniphobic membranes as well as composite membranes with a hydrophobic substrate and a superhydrophilic top surface. We challenged the MD membranes with hypersaline feed solutions that contained a relatively high concentration of crude oil with and without added synthetic surfactants, Triton X-100. We found that the composite membranes with superhydrophilic top surface were robustly resistant to oil fouling in the absence of Triton X-100, but were subject to pore wetting in the presence of Triton X-100. On the other hand, the omniphobic membranes were easily fouled by oil-in-water emulsion without Triton X-100, but successfully sustained stable MD performance with Triton X-100 stabilized oil-in-water emulsion as the feed solution. In contrast, the conventional hydrophobic membranes failed readily regardless whether Triton X-100 was present, although via different mechanisms. These findings are corroborated by contact angle measures as well as oil-probe force spectroscopy. This study provides a holistic picture regarding how a hydrophobic membrane fails in MD and how we can leverage membranes with special wettability to prevent membrane failure in MD operations.

  15. Fouling and thermal-performance characteristics of the Humboldt Bay Unit 2 power-plant condenser

    Energy Technology Data Exchange (ETDEWEB)

    Rabas, T.J. [Argonne National Lab., IL (United States); Elliott, E.S. [Pacific Gas and Electric Co., San Ramon, CA (US)

    1993-07-01

    An experimental program was conducted at the Humboldt Bay condenser using eight clusters of four neighboring tubes with different conditions. In each cluster, there were (1) a new tube, the tubeside fluid being distilled water; (2) a new tube, the tubeside fluid being plant circulating water (seawater) and no cleaning; (3) an old tube, plant circulating water with no cleaning; and (4) an old tube, plant circulating water with normal periodic manual cleaning (blowing plugs or sponge balls). These tube clusters were located at four different locations within both the first and second passes of this two-pass condenser. Because of the different conditions, the fouling and cleaning characteristics can be obtained with measurements of the flow rate and inlet, outlet, and saturation temperatures. In addition to the fouling data, the thermal performance can be compared to that obtained with the standard rating method. There was a reduction in the thermal performance of the new, distilled-water tubes for about the first 80 days, and then the performance remained essentially constant. This performance change was most likely the result of the change from dropwise to filmwise condensation on the 7/8-in OD, 18 BWG Admiralty tubes. There was a continued increase of the tubeside fouling resistance with time (no asymptotic behavior) for the tubes that were not cleaned in each cluster using the plant circulating water. The fouling rates were somewhat larger for the first or lower temperature pass initially for the new tubes and after about 100 days for the old tubes. However, the fouling resistance values were substantially larger for the old tubes.

  16. Fouling Communities of Two Accidental Artificial Reefs (Modern Shipwrecks in Cyprus (Levantine Sea

    Directory of Open Access Journals (Sweden)

    Carlos Jimenez

    2016-12-01

    Full Text Available Artificial reefs are considered one of the alternative methods in fisheries management, used in order to enhance stocks and marine biodiversity in general. A number of biotic and abiotic parameters influence the fouling communities’ formation on artificial reefs through complex interactions. In order to understand how epibiotic or fouling communities progress through time, it is important to study these communities in mature artificial reefs, especially those that have been around for many decades, or in some cases, millennia. This study was conducted on the coral and other fouling organisms of two accidental artificial reefs (40 to 70 year-old shipwrecks in Cyprus (Levantine Sea. The thermal and nutrient annual regime of the study sites were characterized by processing satellite data. The results indicate that the wrecks are normally under warm and oligotrophic conditions. Percentage coverage of corals and other organisms on the wrecks was calculated (image-analysis software on photos taken in 2010 (two wrecks and again in 2016 (one wreck of the fouling communities. Sponges were the organisms with the highest percent cover (~27% at the two wrecks. Four scleractinian coral species were found (7%–19% total coral cover. The oldest wreck, which has well-developed coral communities, was revisited during fieldwork in a near-by area in 2016. Only two major benthic categories (dead coral and macro algae changed significantly between sampling periods. Given the actual policies to sink wrecks to create artificial reefs and the diverse environmental conditions in different areas that will inevitably influence fouling, it is important to carry out studies relating to mature artificial reefs/wrecks in order to be able to assess the ecological effectiveness of longstanding artificial reefs.

  17. Trophic structure of the fouling community in Odessa Bay (Black Sea

    Directory of Open Access Journals (Sweden)

    A. Y. Varigin

    2016-06-01

    Full Text Available The trophic structure of the coastal fouling community of Odessa Bay (Black Sea, which was composed of 10 species of macrophytes, 57 invertebrate species and 4 species of fish, was determined. The basic trophic relationship between organisms composing the community is shown. A minimization of interspecific trophic competition within the community is noted. The main sources of food material entering the fouling community were determined. We show that a significant proportion of food in the form of detritus, dissolved organic matter and small planktonic organisms enters the community from the water column. Filtration and pumping activity of sestonophage-organisms, particularly mussels, helps to attract food material to the community. Primary producers of the community are macrophytes and microphytes, which develop on account of their photosynthetic activity and ensure the provision of food to herbivores. The trophic group of detritophages consumes different fractions of the detritus which accumulates in the byssus threads of bivalve molluscs. In this context, mussel druses act as sediment traps, collecting detritus. Numerous polyphages, which are essentially omnivores and do not usually lack food material, were noted in the community. A small group of carnivorous invertebrates, whose representatives actively attack small animals, was identified. The abundance of these species in the community was about 1%, and their biomass less than 0.6%. Fish living in macrophyte weeds are the consumers in the community. We determined that the highest relative abundance (over 36% in the fouling community was reached by sestonophages and polyphages. We found that the undisputed leader in the relative biomass (over 97% in the fouling community ofOdessaBaywas the sestonophages (mainly composed of mussels. We determined that the trophic structure index of the community was 0.94, which confirms the significant dominance in biomass of bivalves over other species in

  18. A semi-empirical model for the prediction of fouling in railway ballast using GPR

    Science.gov (United States)

    Bianchini Ciampoli, Luca; Tosti, Fabio; Benedetto, Andrea; Alani, Amir M.; Loizos, Andreas; D'Amico, Fabrizio; Calvi, Alessandro

    2016-04-01

    The first step in the planning for a renewal of a railway network consists in gathering information, as effectively as possible, about the state of the railway tracks. Nowadays, this activity is mostly carried out by digging trenches at regular intervals along the whole network, to evaluate both geometrical and geotechnical properties of the railway track bed. This involves issues, mainly concerning the invasiveness of the operations, the impacts on the rail traffic, the high costs, and the low levels of significance concerning such discrete data set. Ground-penetrating radar (GPR) can represent a useful technique for overstepping these issues, as it can be directly mounted onto a train crossing the railway, and collect continuous information along the network. This study is aimed at defining an empirical model for the prediction of fouling in railway ballast, by using GPR. With this purpose, a thorough laboratory campaign was implemented within the facilities of Roma Tre University. In more details, a 1.47 m long × 1.47 m wide × 0.48 m height plexiglass framework, accounting for the domain of investigation, was laid over a perfect electric conductor, and filled up with several configuration of railway ballast and fouling material (clayey sand), thereby representing different levels of fouling. Then, the set of fouling configurations was surveyed with several GPR systems. In particular, a ground-coupled multi-channel radar (600 MHz and 1600 MHz center frequency antennas) and three air-launched radar systems (1000 MHz and 2000 MHz center frequency antennas) were employed for surveying the materials. By observing the results both in terms of time and frequency domains, interesting insights are highlighted and an empirical model, relating in particular the shape of the frequency spectrum of the signal and the percentage of fouling characterizing the surveyed material, is finally proposed. Acknowledgement The Authors thank COST, for funding the Action TU1208 "Civil

  19. Numerical Investigation of Simultaneously Deposition and Re-Entrainment Fouling Processes in Corrugated Tubes by Coupling CFD and DEM

    DEFF Research Database (Denmark)

    Hærvig, Jakob; Condra, Thomas Joseph; Sørensen, Kim

    The deposition of particulate fouling on flue gas heat exchanger surfaces results in decreased heat transfer. Even though an increasingly amount of work is done on the design of clean heat exchanger surfaces, the effect of fouling remains a challenge. As some heat exchanger designs are more prone...... Computational Fluid Dynamics (CFD) software OpenFOAM is coupled to the Discrete Element Method (DEM) software LIGGGHTS using the coupling software CFDEM. A four-way coupling is used to model fluid-particle and particle-particle interactions and thereby allowing for a particle fouling layer to build up along...

  20. Filtration behavior of casein glycomacropeptide (CGMP) in an enzymatic membrane reactor: fouling control by membrane selection and threshold flux operation

    DEFF Research Database (Denmark)

    Luo, Jianquan; Morthensen, Sofie Thage; Meyer, Anne S.

    2014-01-01

    . In this study, the filtration performance and fouling behavior during ultrafiltration (UF) of CGMP for the enzymatic production of 3′-sialyllactose were investigated. A 5kDa regenerated cellulose membrane with high anti-fouling performance, could retain CGMP well, permeate 3′-sialyllactose, and was found...... concentration on the threshold flux were studied based on the resistance-in-series model. Higher hydrophilicity of the membrane, elevated pH and agitation, and lower CGMP concentration were found to increase the threshold flux and decrease membrane fouling....

  1. Role and levels of real-time monitoring for successful anti-fouling strategies--an overview.

    Science.gov (United States)

    Flemming, H C

    2003-01-01

    Biofouling is a biofilm problem and any anti-fouling strategy will be greatly improved if the site and extent of biofilm growth can be monitored. A suitable monitoring system will provide early warning capacity and allow for specific optimization of countermeasures. As water samples do not give reliable information about biofilms, surface sampling is mandatory. Conventional biofilm monitoring techniques rely on removal of material from representative sites or on analysis of test surfaces which have been exposed. This procedure is time consuming and, depending on the parameters to be measured, requires skilled laboratory personnel. There is a strong demand for direct, on-line, in situ, continuous, non-destructive real-time information about biofilms in a system. Such demands can only be fulfilled by physical or physico-chemical methods, a number of which have already been successfully applied for biofilm monitoring. It is important, however, to be aware of the actual parameter they refer to in order to interpret the data properly. Three levels of information can be identified: (i) systems which detect increase and decrease of material accumulating on a surface but cannot differentiate between biomass and other components of a deposit, (ii) systems which provide biological information and distinguish between biotic and abiotic material, and (iii) systems which provide detailed chemical information. Examples for all three levels are presented and discussed.

  2. Anti-fouling surfaces by combined molecular self-assembly and surface-initiated ATRP for micropatterning active proteins.

    Science.gov (United States)

    Xiu, K M; Cai, Q; Li, J S; Yang, X P; Yang, W T; Xu, F J

    2012-02-01

    A simple method by combined molecular self assembly and surface-initiated atom transfer radical polymerization (SI-ATRP) was proposed to prepare a biologically inert surface for micropatterning active proteins. The MPEG microdomains having a short terminal poly(ethylene glycol) (PEG) unit were prepared by self assembly of 2-(methyoxy(polyethylenoxy) propyl)trimethoxy silane (MPEG-silane). The remaining local regions or poly(poly(ethylene glycol)methyl ether methacrylate-co-glycidyl methacrylate) (P(PEGMEMA-co-GMA)) microdomains were produced via SI-ATRP of PEGMEMA and GMA comonomers. The epoxy groups of the P(PEGMEMA-co-GMA) microdomains were used directly for covalent coupling of an active protein (human immunoglobulin or IgG) via the ring-opening reaction to produce the IgG-coupled microdomains. The IgG-coupled microdomains interact only and specifically with target anti-IgG, while the other antifouling microregions from self-assembled monolayers with short terminal PEG units effectively prevent specific and non-specific protein fouling. When extended to other active biomolecules, microarrays for specific and non-specific analyte interactions with a high signal-to-noise ratio could be readily tailored.

  3. Contribution of Fe3O4 nanoparticles to the fouling of ultrafiltration with coagulation pre-treatment

    Science.gov (United States)

    Yu, Wenzheng; Xu, Lei; Graham, Nigel; Qu, Jiuhui

    2015-08-01

    A coagulation (FeCl3)-ultrafiltration process was used to treat two different raw waters with/without the presence of Fe3O4 nanoparticle contaminants. The existence of Fe3O4 nanoparticles in the raw water was found to increase both irreversible and reversible membrane fouling. The trans-membrane pressure (TMP) increase was similar in the early stages of the membrane runs for both raw waters, while it increased rapidly after about 15 days in the raw water with Fe3O4 nanoparticles, suggesting the involvement of biological effects. Enhanced microbial activity with the presence of Fe3O4 nanoparticles was evident from the measured concentrations of extracellular polymeric substances (EPS) and deoxyribonucleic acid (DNA), and fluorescence intensities. It is speculated that Fe3O4 nanoparticles accumulated in the cake layer and increased bacterial growth. Associated with the bacterial growth is the production of EPS which enhances the bonding with, and between, the coagulant flocs; EPS together with smaller sizes of the nano-scale primary particles of the Fe3O4-CUF cake layer, led to the formation of a lower porosity, more resilient cake layer and membrane pore blockage.

  4. Toxicity of anti-fouling paints for use on ships and leisure boats to non-target organisms representing three trophic levels.

    Science.gov (United States)

    Karlsson, Jenny; Ytreberg, Erik; Eklund, Britta

    2010-03-01

    Leachates of anti-fouling paints for use on ships and leisure boats are examined for their ecotoxicological potential. Paint leachates were produced in both 7 per thousand artificial (ASW) and natural seawater (NSW) and tested on three organisms, the bacterium Vibrio fischeri, the macroalga Ceramium tenuicorne, and the crustacean Nitocra spinipes. Generally, leaching in ASW produced a more toxic leachate and was up to 12 times more toxic to the organisms than was the corresponding NSW leachate. The toxicity could be explained by elevated concentrations of Cu and Zn in the ASW leachates. Of the NSW leachates, those from the ship paints were more toxic than those from leisure boat paints. The most toxic paint was the biocide-free leisure boat paint Micron Eco. This implies that substances other than added active agents (biocides) were responsible for the observed toxicity, which would not have been discovered without the use of biological tests.

  5. Effect of solid retention time on membrane fouling in membrane bioreactor: from the perspective of quorum sensing and quorum quenching.

    Science.gov (United States)

    Yu, Huarong; Xu, Guoren; Qu, Fangshu; Li, Guibai; Liang, Heng

    2016-09-01

    Solid retention time (SRT) is one of the most important operational parameters in membrane bioreactor (MBR), which significantly influences membrane fouling. It is widely recognized that SRT mainly changes biomass characteristics, and then, influences membrane fouling. Effect of SRT on quorum sensing (QS) in MBR, which could also influence fouling by coordinating biofilm formation, has not been reported. In this study, fouling, QS, soluble microbial products (SMP), and extracellular polymer substances (EPS) in MBRs operated under SRTs of 4, 10, and 40 days were investigated. The results showed that as SRT increased, the abundance of quorum quenching (QQ) bacteria increased, the quorum signal degradation activity of activated sludge increased, the concentrations of signal molecules in MBR decreased, the excretion of SMP and EPS decreased, and thus membrane biofouling was alleviated. Therefore, besides altering the biomass physiochemical properties, SRT also changed the balance between QS and QQ in MBR, and in this way, influenced membrane biofouling.

  6. Growth inhibition of fouling bacteria and diatoms by extract of terrestrial plant, Derris scandens (Dicotyledonae:Leguminocae)

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Sonak, S.; Garg, A.

    Methanol extract of terrestrial plant, Derris scandens Benth, was found to inhibit growth of four diatoms and 7 bacterial species of fouling community. The concentrations required to bring about 100% inhibition of growth of the diatoms ranged...

  7. Fouling and cleaning characteristics of ultrafiltration of hydrophobic dissolved organic matter by a polyvinyl chloride hollow fiber membrane.

    Science.gov (United States)

    Guo, Xiaoyan; Gao, Wei; Li, Jihui; Hu, Wanli

    2009-06-01

    Ultrafiltration membrane fouling is a significant problem in drinking water treatment. Many researchers believe that hydrophobic natural organic matter is the main foulant. In this research, fulvic acid, tannin, and aniline were used to represent hydrophobic acid, neutral, and base, respectively, to investigate modified polyvinyl chloride ultrafiltration membrane fouling characteristics. Four kinds of cleaning methods were used in this study: flushing, backwashing, flushing and backwashing, and chemical cleaning with 0.5% sodium hydroxide. Each was performed on the three hydrophobic dissolved organic matters (acid, neutral, and base) to identify the fouling mechanisms of polyvinyl chloride ultrafiltration membrane. Results showed that hydrophobic base fouled membranes the most and hydrophobic acid the least based on cleaning difficulty.

  8. Enhanced fouling by inorganic and organic foulants on pressure retarded osmosis (PRO) hollow fiber membranes under high pressures

    KAUST Repository

    Chen, Sicong

    2015-04-01

    We have studied, for the first time, the fouling behavior of pressure retarded osmosis (PRO) hollow fiber membranes under low, moderate and high hydraulic pressures. The thin film composite (TFC) polyethersulfone (PES) membrane has a high water permeability and good mechanical strength. Membrane fouling by gypsum (CaSO4·2H2O) scalants, sodium alginate, and the combined foulants was examined under various pressures up to an ultrahigh hydraulic pressure of 18bar. In the combined fouling experiments, the membranes were conditioned by one of foulants followed by the other. Flux decline results suggested that such conditioning could increase the rate of combined fouling because of the change in membrane surface chemistry. Specially, the co-existence of gypsum crystals and alginate under 0bar led to the synergistic combined fouling and resulted in a greater flux decline than the sum of individual fouling. Interestingly, such gypsum-alginate synergistic fouling was not observed under high pressure PRO tests because the increased reverse salt flux inhibited the formation of gypsum crystals. Therefore, alginate fouling could be the dominant fouling mechanism for both (1) alginate conditioning and then scalants fouling, and (2) scalants conditioning and then alginate fouling PRO processes under 8bar and 18bar. Since the reverse salt flux increases from 5.6±1.1g/m2h at 0bar to 74.3±9.7g/m2h at 8bar, and finally to 150.5±2.5g/m2h under 18bar, the reverse salt ions lead to substantial declines of normalized flux under 8bar and 18bar because the reverse sodium ions not only reduce the effective driving force across the PRO membrane but also induce a significant cake-enhanced sodium concentration polarization layer and facilitate alginate gelation near the membrane surface. Therefore, the removal of alginate type foulants from the feed water stream may become essential for the success of PRO processes under high pressures.

  9. A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors

    Science.gov (United States)

    Huang, Jian; Wang, Zhiwei; Zhang, Junyao; Zhang, Xingran; Ma, Jinxing; Wu, Zhichao

    2015-03-01

    Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

  10. Organic fouling of thin-film composite polyamide and cellulose triacetate forward osmosis membranes by oppositely charged macromolecules.

    Science.gov (United States)

    Gu, Yangshuo; Wang, Yi-Ning; Wei, Jing; Tang, Chuyang Y

    2013-04-01

    Fouling of cellulose triacetate (CTA) and thin-film composite (TFC) forward osmosis (FO) membranes by organic macromolecules were studied using oppositely charged lysozyme (LYS) and alginate (ALG) as model foulants. Flux performance and foulant deposition on membranes were systematically investigated for a submerged membrane system. When an initial flux of 25 L/m(2)h was applied, both flux reduction and foulant mass deposition were severe for feed water containing the mixture of LYS and ALG (e.g., 50% LYS and 50% ALG at a total foulant concentration of 100 mg/L). In comparison, fouling was much milder for feed water containing either LYS or ALG alone. Compared to the CTA FO membrane, the TFC FO membrane showed greater fouling propensity under mild FO fouling conditions due to its much rougher surface. Nevertheless, under severe FO fouling conditions, fouling was dominated by foulant-deposited-foulant interaction and membrane surface properties played a less important role. Furthermore, when the feed water contained both LYS and ALG in sufficient amount, the deposited cake layer foulant composition (i.e., the LYS/ALG mass ratio) was not strongly affected by membrane types (CTA versus TFC) nor testing modes (pressure-driven NF mode versus osmosis-driven FO mode). In contrast, solution chemistry such as pH and calcium concentration had remarkable effect on the cake layer composition due to their effects on foulant-foulant interaction.

  11. Formation of fouling deposits on a carbon steel surface from Colombian heavy crude oil under preheating conditions

    Science.gov (United States)

    Muñoz Pinto, D. A.; Cuervo Camargo, S. M.; Orozco Parra, M.; Laverde, D.; García Vergara, S.; Blanco Pinzon, C.

    2016-02-01

    Fouling in heat exchangers is produced by the deposition of undesired materials on metal surfaces. As fouling progresses, pressure drop and heat transfer resistance is observed and therefore the overall thermal efficiency of the equipment diminishes. Fouling is mainly caused by the deposition of suspended particles, such as those from chemical reactions, crystallization of certain salts, and some corrosion processes. In order to understand the formation of fouling deposits from Colombian heavy oil (API≈12.3) on carbon steel SA 516 Gr 70, a batch stirred tank reactor was used. The reactor was operated at a constant pressure of 340psi while varying the temperature and reaction times. To evaluate the formation of deposits on the metal surfaces, the steel samples were characterized by gravimetric analysis and Scanning Electron Microscopy (SEM). On the exposed surfaces, the results revealed an increase in the total mass derived from the deposition of salt compounds, iron oxides and alkaline metals. In general, fouling was modulated by both the temperature and the reaction time, but under the experimental conditions, the temperature seems to be the predominant variable that controls and accelerates fouling.

  12. Towards a better hydraulic cleaning strategy for ultrafiltration membrane fouling by humic acid: Effect of backwash water composition.

    Science.gov (United States)

    Chang, Haiqing; Liang, Heng; Qu, Fangshu; Ma, Jun; Ren, Nanqi; Li, Guibai

    2016-05-01

    As a routine measurement to alleviate membrane fouling, hydraulic cleaning is of great significance for the steady operation of ultrafiltration (UF) systems in water treatment processes. In this work, a comparative study was performed to investigate the effects of the composition of backwash water on the hydraulic cleaning performance of UF membranes fouled by humic acid (HA). Various types of backwash water, including UF permeate, Milli-Q water, NaCl solution, CaCl2 solution and HA solution, were compared in terms of hydraulically irreversible fouling index, total surface tension and residual HA. The results indicated that Milli-Q water backwash was superior to UF permeate backwash in cleaning HA-fouled membranes, and the backwash water containing Na(+) or HA outperformed Milli-Q water in alleviating HA fouling. On the contrary, the presence of Ca(2+) in backwash water significantly decreased the backwash efficiency. Moreover, Ca(2+) played an important role in foulant removal, and the residual HA content closely related to the residual Ca(2+) content. Mechanism analysis suggested that the backwash process may involve fouling layer swelling, ion exchange, electric double layer release and competitive complexation. Ion exchange and competitive complexation played significant roles in the efficient hydraulic cleaning associated with Na(+) and HA, respectively.

  13. Impacts of sludge retention time on sludge characteristics and membrane fouling in a submerged anaerobic-oxic membrane bioreactor.

    Science.gov (United States)

    Zhang, Xiaomei; Yue, Xiuping; Liu, Zhiqiang; Li, Qingqing; Hua, Xiufu

    2015-06-01

    Anaerobic-oxic membrane bioreactor (AOMBR) has been proposed as a highly effective method in municipal and industrial wastewater treatment. In this study, according to the sewage treatment system in a campus, long-term experiments were conducted to assess the impacts of the sludge retention time (SRT) on sludge characteristics and membrane fouling, and the sludge parameters include biomass concentration, particle size distribution, extracellular polymeric substances (EPS), soluble microbial products (SMPs), and specific resistance to filtration (SRF). Our results clearly demonstrated that SRT was one of the most important factors influencing sludge characteristics, and different sludge characteristics resulted in different membrane fouling degrees. A better treatment and filtration performances were observed at the SRT of 30 days compared to two SRTs of 10 and 90 days. Among these parameters, SMP had the most significant correlation with the membrane fouling rate (dTMP/dt), and it had a negative impact on membrane filtration performance. The impact of SRT on membrane fouling process was discussed further by filtration models. At 10 days SRT, the complete-standard blocking model curve had a comparatively higher goodness-of-fit with the fouling process, and at 30 and 90 days SRT, the cake-standard blocking model curve had a relatively higher goodness-of-fit with respective fouling process.

  14. Audience Perception of Hate Speech and Foul Language in the Social Media in Nigeria: Implications for Morality and Law

    Directory of Open Access Journals (Sweden)

    Terfa T. Alakali

    2017-01-01

    Full Text Available This paper examined the phenomenon of hate speech and foul language on social media platforms in Nigeria, and assessed their moral and legal consequences in the society and to journalism practice. It used both quantitative and qualitative methodology to investigate the phenomenon. In the first place, the paper employed the survey research methodology to sample 384 respondents using questionnaire and focus group discussion as instruments for data collection. Findings from the research indicate that promoting hate speech and foul language on social media have moral and legal consequences in the society and to journalism practice. Findings also show that although, the respondents understand that hate speech and foul language attract legal consequences, they do not know what obligations are created by law against perpetrators of hate speech and foul language in Nigeria. The paper therefore, adopted the qualitative, doctrinal and analytical methodology to discuss the legal consequences and obligations created against perpetrators of hate speech and foul language in Nigeria. The paper concluded based on the findings that hate speech and foul language is prevalent on social media platforms in Nigeria and that there are adequate legal provisions to curb the phenomenon in Nigeria. It recommends among others things that the Nigerian government and NGOs should sponsor monitoring projects like the UMATI in Kenya to better understand the use of hate speech and that monitoring agencies set up under the legal regime should adopt mechanisms to identify and remove hate speech content on social media platforms in Nigeria.

  15. A practical ranking system to compare toxicity of anti-fouling paints.

    Science.gov (United States)

    Karlsson, Jenny; Breitholtz, Magnus; Eklund, Britta

    2006-12-01

    The toxicity of a number of new anti-fouling paints, claimed to function by physical means and not by leakage of toxic substances, have been tested on two common organisms in the Baltic Sea, i.e., the red macro alga Ceramium tenuicorne and the copepod Nitocra spinipes. In order to compare the toxicity between the paints a ranking system was developed based on the EC(50)- and LC(50)-values. The results showed a wide span in toxicity with the most toxic paints ranked 160 times more toxic than the ones ranked least toxic. Also, TBT, irgarol and diuron, which have been used as active ingredients in traditional anti-fouling paints, were used to evaluate the sensitivity of the two test organisms. The results showed that the test organisms were equally sensitive to the substances as similar organisms in earlier studies. In conclusion, the ranking system presented in this study permits ranking and comparison of total toxicity of complex mixtures.

  16. Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

    KAUST Repository

    Fang, Jason

    2010-05-01

    The bulk and surface characteristics of a series of coatings based on PDMS-polyurea segmented copolymers were correlated to their fouling release performance. Incorporation of polyurea segments to PDMS backbone gives rise to phase separation with the extensively hydrogen bonded hard domains creating an interconnected network that imparts mechanical rigidity. Increasing the compositional complexity of the system by including fluorinated or POSS-functionalized chain extenders or through nanoclay intercalation, confers further thermomechanical improvements. In analogy to the bulk morphology, the surface topography also reflects the compositional complexity of the materials, displaying a wide range of motifs. Investigations on settlement and subsequent removal of Ulva sporelings on those nanostructured surfaces indicate that the work required to remove the microorganisms is significantly lower compared to coatings based on standard PDMS homopolymer. All in all, the series of materials considered in this study demonstrate advanced fouling release properties, while exhibiting superior mechanical properties and, thus, long term durability. © 2010 Elsevier Ltd.

  17. Zwitterionic glycosyl modified polyethersulfone membranes with enhanced anti-fouling property and blood compatibility.

    Science.gov (United States)

    Xie, Yi; Li, Shuang-Si; Jiang, Xin; Xiang, Tao; Wang, Rui; Zhao, Chang-Sheng

    2015-04-01

    In this study, novel zwitterionic glycosyl modified polyethersulfone (PES) ultrafiltration membranes were prepared via in-situ cross-linking polymerization coupled with phase inversion technique, and the following reactions. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), (1)HNMR spectrum, and static water contact angles (WCAs) measurements. The modified membranes showed excellent anti-fouling property, and the flux recovery ratio could reach almost 100%. Meanwhile, the blood compatibility of the membranes was measured by protein adsorption, platelet adhesion, activated partial thromboplastin time (APTT), and thrombin time (TT). The results implied that the zwitterionic glycosyl modified PES membranes had good anti-fouling property and blood compatibility.

  18. A robust way to prepare blood-compatible and anti-fouling polyethersulfone membrane.

    Science.gov (United States)

    Xie, Yi; Wang, Rui; Li, Shuangsi; Xiang, Tao; Zhao, Chang-Sheng

    2016-10-01

    Functional copolymers were successfully grafted onto polyethersulfone (PES) membrane surfaces by free radical mechanism using ammonium persulfate (APS) as an initiator. The anti-coagulant and anti-fouling properties of the membranes were well controlled by changing the functional copolymer compositions. Attenuated total reflection-Fourier transforminfrared (ATR-FTIR), X-ray photoelectron spectrometer spectrum (XPS), water contact angles (WCAs), and scanning electron microscopy (SEM) images were used to characterize the membranes. The results of protein adsorption, clotting times, platelet adhesion and bacteria attachment indicated that the membranes had good blood-compatibility and/or anti-fouling ability. Meanwhile, the modification didn't cause an adverse effect on the membrane permeability. This new method provides a general, robust and flexible way to adjust membrane surface performance and potentially has wide applications.

  19. Fouling and the inhibition of salt corrosion. [hot corrosion of superalloys

    Science.gov (United States)

    Deadmore, D. L.; Lowell, C. E.

    1980-01-01

    In an attempt to reduce fouling while retaining the beneficial effects of alkaline earth inhibitors on the hot corrosion of superalloys, the use of both additives and the intermittent application of the inhibitors were evaluated. Additions of alkaline earth compounds to combustion gases containing sodium sulfate were shown to inhibit hot corrosion. However, sulfate deposits can lead to turbine fouling in service. For that reason, dual additives and intermittant inhibitor applications were evaluated to reduce such deposit formation. Silicon in conjunction with varium showed some promise. Total deposition was apparently reduced while the inhibition of hot corrosion by barium was unimpaired. The intermittant application of the inhibitor was found to be more effective and controllable.

  20. Clarification of purple carrot juice: analysis of the fouling mechanisms and evaluation of the juice quality.

    Science.gov (United States)

    Ennouri, Monia; Ben Hassan, Ines; Ben Hassen, Hanen; Lafforgue, Christine; Schmitz, Philippe; Ayadi, Abdelmoneim

    2015-05-01

    Purple carrot juice was clarified by microfiltration. Two modes of filtration, batch concentration and total recycle were tested and the effect of microfiltration process on permeate flux and membrane fouling was studied. Intrinsic membrane resistance was negligible compared with the fouling resistances, which was less than 5 % of total resistance. Determination of membrane hydraulic permeability showed that water cleaning could permit a recovery of about 7 % of initial hydraulic flux. The analysis of color parameters of feed, permeate and concentrate juice during filtration shows that the a* and b* values decrease for the permeate corresponding respectively to changes from green to red and from blue to yellow. The total sugar and reducing sugars increase in permeate and decrease in concentrate. This work showed that it was possible to clarify the purple carrot juice by microfiltration with a real amelioration of the juice appearance.

  1. Fabrication of anti-protein-fouling poly(ethylene glycol) microfluidic chip electrophoresis by sandwich photolithography.

    Science.gov (United States)

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Liu, Huwei; Yuan, Hua

    2016-07-01

    Microfluidic chip electrophoresis (MCE) is a powerful separation tool for biomacromolecule analysis. However, adsorption of biomacromolecules, particularly proteins onto microfluidic channels severely degrades the separation performance of MCE. In this paper, an anti-protein-fouling MCE was fabricated using a novel sandwich photolithography of poly(ethylene glycol) (PEG) prepolymers. Photopatterned microchannel with a minimum resolution of 10 μm was achieved. After equipped with a conventional online electrochemical detector, the device enabled baseline separation of bovine serum albumin, lysozyme (Lys), and cytochrome c (Cyt-c) in 53 s under a voltage of 200 V. Compared with a traditional polydimethylsiloxane MCE made by soft lithography, the PEG MCE made by the sandwich photolithography not only eliminated the need of a master mold and the additional modification process of the microchannel but also showed excellent anti-protein-fouling properties for protein separation.

  2. Applying thermosettable zwitterionic copolymers as general fouling-resistant and thermal-tolerant biomaterial interfaces.

    Science.gov (United States)

    Chou, Ying-Nien; Chang, Yung; Wen, Ten-Chin

    2015-05-20

    We introduced a thermosettable zwitterionic copolymer to design a high temperature tolerance biomaterial as a general antifouling polymer interface. The original synthetic fouling-resistant copolymer, poly(vinylpyrrolidone)-co-poly(sulfobetaine methacrylate) (poly(VP-co-SBMA)), is both thermal-tolerant and fouling-resistant, and the antifouling stability of copolymer coated interfaces can be effectively controlled by regulating the VP/SBMA composition ratio. We studied poly(VP-co-SBMA) copolymer gels and networks with a focus on their general resistance to protein, cell, and bacterial bioadhesion, as influenced by the thermosetting process. Interestingly, we found that the shape of the poly(VP-co-SBMA) copolymer material can be set at a high annealing temperature of 200 °C while maintaining good antifouling properties. However, while the zwitterionic PSBMA polymer gels were bioinert as expected, control of the fouling resistance of the PSBMA polymer networks was lost in the high temperature annealing process. A poly(VP-co-SBMA) copolymer network composed of PSBMA segments at 32 mol % showed reduced fibrinogen adsorption, tissue cell adhesion, and bacterial attachment, but a relatively higher PSBMA content of 61 mol % was required to optimize resistance to platelet adhesion and erythrocyte attachment to confer hemocompatibility to human blood. We suggest that poly(VP-co-SBMA) copolymers capable of retaining stable fouling resistance after high temperature shaping have a potential application as thermosettable materials in a bioinert interface for medical devices, such as the thermosettable coating on a stainless steel blood-compatible metal stent investigated in this study.

  3. Fouling and Boring of Glass Reinforced Plastic - Balsa Blocks in a Tropical Marine Environment,

    Science.gov (United States)

    1983-03-01

    only fouled below the water line, mainly by diminutive algae and a slime film of undetermined composition (possibly bacteria, diatoms and organics... composition . The GRP performed as any hard, smooth, non-toxic substratum immersed in the sea and rapidly accrued a cover of diverse organisms. c. Minahunter... Plastique and suppliid by Australian Klegecell Co., Sydney. Nominal density 130 kg/m 3. Balsa wood imported from Papua-New Guinea and supplied by Australian

  4. Irreversible fouling of membrane bioreactors due to formation of a non-biofilm gel layer

    DEFF Research Database (Denmark)

    Poorasgari, Eskandar; Larsen, Poul; Zheng, Xing

    2014-01-01

    adsorption kinetics. Due to static adsorption, surface roughness of the membrane declined significantly, indicating that adsorbed matters to the membranefilled the cavities of the membrane surface. Filtration of the free EPS caused 50% waterflux decline. The fouling resistance linearly increased...... with the amount of the humic-like substances retained during filtration as predicted by gel growth theory. A low pressure backwash could re-establish the Water flux only up to 70%....

  5. Fouling behavior of microstructured hollow fiber membranes in submerged and aerated filtrations.

    Science.gov (United States)

    Culfaz, P Z; Wessling, M; Lammertink, R G H

    2011-02-01

    The performance of microstructured hollow fiber membranes in submerged and aerated systems was investigated using colloidal silica as a model foulant. The microstructured fibers were compared to round fibers and to twisted microstructured fibers in flux-stepping experiments. The fouling resistances in the structured fibers were found to be higher than those of round fibers. This was attributed to stagnant zones in the grooves of the structured fibers. As the bubble sizes were larger than the size of the grooves of the structured fibers, it is possible that neither the bubbles nor the secondary flow caused by the bubbles can reach the bottom parts of the grooves. Twisting the structured fibers around their axes resulted in decreased fouling resistances. Large, cap-shaped bubbles and slugs were found to be the most effective in fouling removal, while small bubbles of sizes similar to the convolutions in the structured fiber did not cause an improvement in these fibers. Modules in a vertical orientation performed better than horizontal modules when coarse bubbling was used. For small bubbles, the difference between vertical and horizontal modules was not significant. When the structured and twisted fibers were compared to round fibers with respect to the permeate flowrate produced per fiber length instead of the actual flux through the convoluted membrane area, they showed lower fouling resistance than round fibers. This is because the enhancement in surface area is more than the increase in resistance caused by stagnant zones in the grooves of the structured fibers. From a practical point of view, although the microstructure does not promote further turbulence in submerged and aerated systems, it can still be possible to enhance productivity per module with the microstructured fibers due to their high surface area-to-volume ratio.

  6. [Anti-fouling characteristics of the novel precoating reagent in dynamic membrane bioreactor].

    Science.gov (United States)

    Ye, Mao-Sheng; Zhang, Han-Min; Yang, Feng-Lin; Cui, Xia

    2007-11-01

    Further research was made on precoating reagents in dynamic membrane process, in which novel precoating reagent-polyvinyl alcohol microsphere (PVA-MS) was prepared through emulsive polymerization of PVA and glutaraldehyde (GA). Furthermore, polymerization mechanism and anti-fouling characteristics through adsorption of membrane major fouling substances EPS upon PVA-MS were studied. The results showed that hemiacetals reaction played a major role in emulsive polymerization process, as the quantity of hydroxyl on PVA was decreased a little, PVA-MS surface behaved good hydrophilic, and the adsorption of protein and amylose upon PVA microsphere was stable and low, which was 0.543 mg x g(-1) and 0.694 mg x g(-1) respectively. In addition, PVA-MS surface behaved electronic negativity, which acted electrostatic repulsion to active sludge floc. Upon this characteristics and data, it was concluded that membrane fouling was delayed in microscopy structure. Diameter of PVA-MS in precoating liquid was about 1.14 microm, and Zeta-potential of precoating liquid with different precoating reagent concentration was less than - 39 mV, which made PVA microsphere diffused and stable from each other, then sedimentate rapidly on porous support membrane surface and internal wall of hole path. Besides, the morphology of PVA-MS and dynamic membrane formed from PVA-MS on support membrane were observed through SEM.

  7. Alginate fouling reduction of functionalized carbon nanotube blended cellulose acetate membrane in forward osmosis.

    Science.gov (United States)

    Choi, Hyeon-Gyu; Son, Moon; Yoon, SangHyeon; Celik, Evrim; Kang, Seoktae; Park, Hosik; Park, Chul Hwi; Choi, Heechul

    2015-10-01

    Functionalized multi-walled carbon nanotube blended cellulose acetate (fCNT-CA) membranes were synthesized for forward osmosis (FO) through phase inversion. The membranes were characterized through SEM, FTIR, and water contact angle measurement. AFM was utilized to investigate alginate fouling mechanism on the membrane. It reveals that the fCNT contributes to advance alginate fouling resistance in FO (57% less normalized water flux decline for 1% fCNT-CA membrane was observed than that for bare CA membrane), due to enhanced electrostatic repulsion between the membrane and the alginate foulant. Furthermore, it was found that the fCNT-CA membranes became more hydrophilic due to carboxylic groups in functionalized carbon nanotube, resulting in approximately 50% higher water-permeated flux than bare CA membrane. This study presents not only the fabrication of fCNT-CA membrane and its application to FO, but also the quantification of the beneficial role of fCNT with respect to alginate fouling in FO.

  8. Enhancement and Mitigation Mechanisms of Protein Fouling of Ultrafiltration Membranes under Different Ionic Strengths.

    Science.gov (United States)

    Miao, Rui; Wang, Lei; Mi, Na; Gao, Zhe; Liu, Tingting; Lv, Yongtao; Wang, Xudong; Meng, Xiaorong; Yang, Yongzhe

    2015-06-02

    To determine further the enhancement and mitigation mechanisms of protein fouling, filtration experiments were carried out with polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes and bovine serum albumin (BSA) over a range of ionic strengths. The interaction forces, the adsorption behavior of BSA on the membrane surface, and the structure of the BSA adsorbed layers at corresponding ionic strengths were investigated. Results indicate that when the ionic strength increased from 0 to 1 mM, there was a decrease in the PVDF-BSA and BSA-BSA electrostatic repulsion forces, resulting in a higher deposition rate of BSA onto the membrane surface, and the formation of a denser BSA layer; consequently, membrane fouling was enhanced. However, at ionic strengths of 10 and 100 mM, membrane fouling and the BSA removal rate decreased significantly. This was mainly due to the increased hydration repulsion forces, which caused a decrease in the PVDF-BSA and BSA-BSA interaction forces accompanied by a decreased hydrodynamic radius and increased diffusion coefficient of BSA. Consequently, BSA passed more easily through the membrane and into permeate. There was less accumulation of BSA on the membrane surface. A more nonrigid and open structure BSA layer was formed on the membrane surface.

  9. Biocontrol of fouling pests: Effect of diversity, identity and density of control agents.

    Science.gov (United States)

    Atalah, Javier; Newcombe, Emma M; Zaiko, Anastasija

    2016-04-01

    Augmentative biocontrol, using native natural enemies, has been suggested as a promising tool to control marine biofouling pests on artificial structures. However, there are still important knowledge gaps to be addressed before biocontrol can be considered as a management tool. In a field experiment on floating marine structures we examined intra- and interspecific consumer interactions among biocontrol agents on different surface orientations. We tested the effect of identity, density and diversity of three invertebrates (the 11-arm seastar Coscinasterias muricata, the sea urchin Evechinus chloroticus and the gastropod Cook's turban Cookia sulcata) to reduce established biofouling and to prevent fouling growth on defouled surfaces. High densities of biocontrol agents were not more effective at fouling control (cover and biomass) than low densities. Nor did multi-species treatments function more effectively than mono-specific ones. However, biocontrol agent identity was important, with the 11-arm seastar and Cook's turban being the most effective at fouling reduction and prevention, respectively. Surface orientation had a strong effect on the effectiveness of control agents, with the best results obtained on vertical compared to diagonal and underside surfaces. This study confirmed the potential of biocontrol as a management tool for marine pest, indicating that identity is more important than richness and density of control agents. It also highlighted the limitations of this approach on diagonal and underside surfaces, where control agents have limited retention ability.

  10. Soft robotic concepts in catheter design: an on-demand fouling-release urinary catheter.

    Science.gov (United States)

    Levering, Vrad; Wang, Qiming; Shivapooja, Phanindhar; Zhao, Xuanhe; López, Gabriel P

    2014-10-01

    Infectious biofilms are problematic in many healthcare-related devices and are especially challenging and ubiquitous in urinary catheters. This report presents an on-demand fouling-release methodology to mechanically disrupt and remove biofilms, and proposes this method for the active removal of infectious biofilms from the previously inaccessible main drainage lumen of urinary catheters. Mature Proteus mirabilis crystalline biofilms detach from silicone elastomer substrates upon application of strain to the substrate, and increasing the strain rate increases biofilm detachment. The study presents a quantitative relationship between applied strain rate and biofilm debonding through an analysis of biofilm segment length and the driving force for debonding. Based on this mechanism, hydraulic and pneumatic elastomer actuation is used to achieve surface strain selectively within the lumen of prototypes of sections of a fouling-release urinary catheter. Proof-of-concept prototypes of sections of active, fouling-release catheters are constructed using techniques typical to soft robotics including 3D printing and replica molding, and those prototypes demonstrate release of mature P. mirabilis crystalline biofilms (e.g., ≈90%) from strained surfaces. These results provide a basis for the development of a new urinary catheter technology in which infectious biofilms are effectively managed through new methods that are entirely complementary to existing approaches.

  11. Development of an on-line measuring and monitoring system for fouling based on Delphi

    Science.gov (United States)

    Wang, Yuanyuan; Wang, Jianguo

    2010-12-01

    The presence of fouling reduced the heat transfer capability of heat transfer equipments and increased the flow resistance of the medium. Thus the resulting series of economic losses received worldwide attention of the relevant heat transfer industry and countries. For the heating system fouling, direct measurement is nearly impossible. And it is extremely difficulty of structuring mathematic model. Although there are existing monitoring methods, results are not satisfactory. This paper intends to develop a new on-line measuring and monitoring system for heating system fouling. The operating theory of this on-line measuring and monitoring system is based on the soft-sensor technology and Expert System. We select some easily measurements as primary variables, such as pressures, flow rates and temperatures. Through some algorithms, we obtained dozens of secondary variables, for example, the coefficient of flow resistance, the efficiency and cost of heating system and so on. Based on these variables, we construct the knowledge base of this System. This system mainly uses Delphi and Excel as development tools. Now, the system is running well in some heating station, and has reached the expecting result.

  12. Identification of Material Parameters for the Simulation of Acoustic Absorption of Fouled Sintered Fiber Felts

    Directory of Open Access Journals (Sweden)

    Nicolas Lippitz

    2016-08-01

    Full Text Available As a reaction to the increasing noise pollution, caused by the expansion of airports close to residential areas, porous trailing edges are investigated to reduce the aeroacoustic noise produced by flow around the airframe. Besides mechanical and acoustical investigations of porous materials, the fouling behavior of promising materials is an important aspect to estimate the performance in long-term use. For this study, two sintered fiber felts were selected for a long-term fouling experiment where the development of the flow resistivity and accumulation of dirt was observed. Based on 3D structural characterizations obtained from X-ray tomography of the initial materials, acoustic models (Biot and Johnson–Champoux–Allard in the frame of the transfer matrix method were applied to the sintered fiber felts. Flow resistivity measurements and the measurements of the absorption coefficient in an impedance tube are the basis for a fouling model for sintered fiber felts. The contribution will conclude with recommendations concerning the modeling of pollution processes of porous materials.

  13. Butenolide inhibits marine fouling by altering the primary metabolism of three target organisms

    KAUST Repository

    Zhang, Yifan

    2012-06-15

    Butenolide is a very promising antifouling compound that inhibits ship hull fouling by a variety of marine organisms, but its antifouling mechanism was previously unknown. Here we report the first study of butenolides molecular targets in three representative fouling organisms. In the barnacle Balanus (=Amphibalanus) amphitrite, butenolide bound to acetyl-CoA acetyltransferase 1 (ACAT1), which is involved in ketone body metabolism. Both the substrate and the product of ACAT1 increased larval settlement under butenolide treatment, suggesting its functional involvement. In the bryozoan Bugula neritina, butenolide bound to very long chain acyl-CoA dehydrogenase (ACADVL), actin, and glutathione S-transferases (GSTs). ACADVL is the first enzyme in the very long chain fatty acid β-oxidation pathway. The inhibition of this primary pathway for energy production in larvae by butenolide was supported by the finding that alternative energy sources (acetoacetate and pyruvate) increased larval attachment under butenolide treatment. In marine bacterium Vibrio sp. UST020129-010, butenolide bound to succinyl-CoA synthetase β subunit (SCSβ) and inhibited bacterial growth. ACAT1, ACADVL, and SCSβ are all involved in primary metabolism for energy production. These findings suggest that butenolide inhibits fouling by influencing the primary metabolism of target organisms. © 2012 American Chemical Society.

  14. Species interactions within a fouling diatom community: roles of nutrients, initial inoculum and competitive strategies.

    Science.gov (United States)

    Mitbavkar, Smita; Anil, Arga Chandrashekar

    2007-01-01

    Diatoms constitute an important component of the fouling community. Although a lot of work has dealt with the fouling diatom community structure, work on the species interactions within the community is still meagre. In this regard, a study was carried out by transferring natural diatom biofilms into controlled conditions in order to understand the roles of nutrients, initial cell inoculum and seasonal variation in species composition in structuring the fouling diatom community. This community exhibited seasonal variation during the monsoon, post-monsoon and pre-monsoon periods. During each of these seasons, diatom species interactions varied depending upon the species composition. It was observed that excess nutrients favoured those species with comparatively higher growth rates, thereby suppressing the growth of other co-existing species. This competitive trait was found to be effective at an appropriate cell density ratio of the competitive and target species. Understanding such pathways will be useful for modelling the interactions between diatom species in various habitats under different resource conditions.

  15. Fouling of inorganic membrane and flux enhancement in membrane-coupled anaerobic bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, S.H.; Kang, I.J.; Lee, C.H. [Seoul National Univ. (Korea, Republic of). Dept. of Chemical Technology

    1999-03-01

    The fouling mechanism of an inorganic membrane was studied during the operation of a membrane-coupled anaerobic bioreactor (MCAB) when alcohol distillery wastewater was used as a digester feed. It was observed that the fouling mechanism of an inorganic membrane was significantly different from that of conventional membrane filtration processes. The main foulant was identified to be an inorganic precipitate, struvite (MgNH{sub 4}PO{sub 4}{center_dot}6H{sub 2}O), rather than anaerobic microbial flocs. Struvite appears to be precipitated not only on the membrane surface but also inside the membrane pores. The amount of struvite generated during the bioreaction was estimated to be about 2 g/L alcohol distillery wastewater. The inorganic foulant was not easily removed by general physical cleaning such as depressurization, lumen flushing, and backflushing. Based on these findings, the membrane fouling was alleviated and thus flux was enhanced by adopting a backfeeding mode which has dual purpose of feeding and backflushing with particle-free acidic wastewater used as the feed for anaerobic digestion.

  16. The Influence of PEG400 and Acetone on Polysulfone Membrane Morphology and Fouling Behaviour

    Directory of Open Access Journals (Sweden)

    P.T.P. Aryanti

    2016-05-01

    Full Text Available Modification of polysulfone ultrafiltration membrane was conducted by blending polysulfone with PEG400 and acetone as additives. The influence of each additive on the resulted membrane morphology and fouling characteristics were investigated. The experimental results showed that the hydrophilicity of the polysulfone membrane was improved by the increase of PEG400 in the polysulfone membrane. The water contact angle of the membrane was decreased from 76.1° to 38.31° when 35 %wt of PEG400 was added into the polysulfone solution, while the water content of the membrane was increased by around 38%. The high concentration of PEG400 in the polysulfone solution led to the formation of longer finger-like cavities in the membrane structure and resulted in a thicker membrane skin layer. The high concentration of PEG400 also contributed to the increase in hydraulic resistance of the membrane due to organic matter fouling. This problem could be minimized by the addition of acetone into the polysulfone solution, which resulted in a lower fouling resistance of organic matter during up to five hours of peat water filtration.

  17. Data on photo-nanofiller models for self-cleaning foul release coating of ship hulls.

    Science.gov (United States)

    Selim, Mohamed S; El-Safty, Sherif A; El-Sockary, Maher A; Hashem, Ahmed I; Abo Elenien, Ossama M; El-Saeed, Ashraf M; Fatthallah, Nesreen A

    2016-09-01

    The data presented in this article are related to the research article entitled "Smart photo-induced silicone/TiO2 nanocomposites with dominant [110] exposed surfaces for self-cleaning foul-release coatings of ship hulls" (Selimet al., 2016) [1]. This article reports on successfully designing and controlling TiO2 spherical single crystal photo-nanofillers and indicating evidence of fouling resistance after stimulation through UV radiation exposure. These data also reveal that the influence of well-dispersed spherical TiO2 nanoparticles (NPs) into the polymer matrix surface features on the prepared fouling release (FR) coating. Single crystal TiO2 nanospheres have played a large role in the scenario of photocatalysis due to its cost effectiveness, inert nature and photo stability. The model output and the surface and mechanical behavior data of the fabricated UV-irradiated silicone-based FR nanocoatings are made publicly available through analyzing nanocomposite topology, superhydrophilicity and self-cleaning efficiency in order to enable critical analysis of the tailored model. It also investigates the photo-bactericidal effect confirmed through biofilm coverage data disability. The modeled nanocomposites were subjected to comparable studies with other published models so as to understand how different UV-irradiated nano-scale parameters propagate and affect bulk film response.

  18. Composite Membrane with Underwater-Oleophobic Surface for Anti-Oil-Fouling Membrane Distillation.

    Science.gov (United States)

    Wang, Zhangxin; Hou, Deyin; Lin, Shihong

    2016-04-05

    In this study, we fabricated a composite membrane for membrane distillation (MD) by modifying a commercial hydrophobic polyvinylidene fluoride (PVDF) membrane with a nanocomposite coating comprising silica nanoparticles, chitosan hydrogel and fluoro-polymer. The composite membrane exhibits asymmetric wettability, with the modified surface being in-air hydrophilic and underwater oleophobic, and the unmodified surface remaining hydrophobic. By comparing the performance of the composite membrane and the pristine PVDF membrane in direct contact MD experiments using a saline emulsion with 1000 ppm crude oil (in water), we showed that the fabricated composite membrane was significantly more resistant to oil fouling compared to the pristine hydrophobic PVDF membrane. Force spectroscopy was conducted for the interaction between an oil droplet and the membrane surface using a force tensiometer. The difference between the composite membrane and the pristine PVDF membrane in their interaction with an oil droplet served to explain the difference in the fouling propensities between these two membranes observed in MD experiments. The results from this study suggest that underwater oleophobic coating can effectively mitigate oil fouling in MD operations, and that the fabricated composite membrane with asymmetric wettability can enable MD to desalinate hypersaline wastewater with high concentrations of hydrophobic contaminants.

  19. Monitoring of polymeric membrane fouling in hollow fiber module using ultrasonic nondestructive testing

    Institute of Scientific and Technical Information of China (English)

    LIU Jing-xia; LI Jian-xin; CHEN Xue-mei; ZHANG Yu-zhong

    2006-01-01

    This study describes the development of novel protocols extending the real-time ultrasonic reflectometry(UTDR) for the detection of membrane fouling in hollow fiber module during ultrafiltration(UF) of oily water treatment. A specially designed acoustic sensor with a frequency of 2.5 MHz was used. The hollow fiber membranes used were polysulphone(PSf) UF membranes with MWCO 40 kDa. The wastewaters with three different oily concentrations of 100,500 and 1 000 mg/L were investigated. Diesel oil was utilized as the primary foulant. The results show that the permeate flux declines with operation time and its value becomes lower with the increase of the oily concentration in wastewater. It is found that ultrasonic measurement can detect the fouling and cleaning processes. A new signal analysis protocol-ultrasonic reflected energy was developed. Ultrasonic reflected energy obtained indicates the deposition of oily layer as a function of operation time and its removal after cleaning. The overall flux decline is reasonably correlated with the changes in ultrasonic reflected energy. This research provides the evidence that the ultrasonic reflectometry technique is capable of monitoring membrane fouling and cleaning in hollow fiber modules.

  20. Effect of makeup water properties on the condenser fouling in power planr cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Safari, I.; Walker, M.; Abbasian, J.; Arastoopour, H.; Hsieh, M-K.; Dzombak, D.; Miller, D.

    2011-01-01

    The thermoelectric power industry in the U.S. uses a large amount of fresh water. As available freshwater for use in thermoelectric power production becomes increasingly limited, use of nontraditional water sources is of growing interest. Utilization of nontraditional water, in cooling systems increases the potential for mineral precipitation on heat exchanger surfaces. In that regard, predicting the accelerated rate of scaling and fouling in condenser is crucial to evaluate the condenser performance. To achieve this goal, water chemistry should be incorporated in cooling system modeling and simulation. This paper addresses the effects of various makeup water properties on the cooling system, namely pH and aqueous speciation, both of which are important factors affecting the fouling rate in the main condenser. Detailed modeling of the volatile species desorption (i.e. CO{sub 2} and NH{sub 3}), the formation of scale in the recirculating system, and the relationship between water quality and the corresponding fouling rates is presented.

  1. Data on photo-nanofiller models for self-cleaning foul release coating of ship hulls

    Directory of Open Access Journals (Sweden)

    Mohamed S. Selim

    2016-09-01

    Full Text Available The data presented in this article are related to the research article entitled “Smart photo-induced silicone/TiO2 nanocomposites with dominant [110] exposed surfaces for self-cleaning foul-release coatings of ship hulls” (Selimet al., 2016 [1]. This article reports on successfully designing and controlling TiO2 spherical single crystal photo-nanofillers and indicating evidence of fouling resistance after stimulation through UV radiation exposure. These data also reveal that the influence of well-dispersed spherical TiO2 nanoparticles (NPs into the polymer matrix surface features on the prepared fouling release (FR coating. Single crystal TiO2 nanospheres have played a large role in the scenario of photocatalysis due to its cost effectiveness, inert nature and photo stability. The model output and the surface and mechanical behavior data of the fabricated UV-irradiated silicone-based FR nanocoatings are made publicly available through analyzing nanocomposite topology, superhydrophilicity and self-cleaning efficiency in order to enable critical analysis of the tailored model. It also investigates the photo-bactericidal effect confirmed through biofilm coverage data disability. The modeled nanocomposites were subjected to comparable studies with other published models so as to understand how different UV-irradiated nano-scale parameters propagate and affect bulk film response.

  2. Studies of polypropylene membrane fouling during microfiltration of broth with Citrobacter freundii bacteria

    Directory of Open Access Journals (Sweden)

    Gryta Marek

    2015-12-01

    Full Text Available In this work a fouling study of polypropylene membranes used for microfiltration of glycerol solutions fermented by Citrobacter freundii bacteria was presented. The permeate free of C. freundii bacteria and having a turbidity in the range of 0.72–1.46 NTU was obtained. However, the initial permeate flux (100–110 L/m2h at 30 kPa of transmembrane pressure was decreased 3–5 fold during 2–3 h of process duration. The performed scanning electron microscope observations confirmed that the filtered bacteria and suspensions present in the broth formed a cake layer on the membrane surface. A method of periodical module rinsing was used for restriction of the fouling influence on a flux decline. Rinsing with water removed most of the bacteria from the membrane surface, but did not permit to restore the initial permeate flux. It was confirmed that the irreversible fouling was dominated during broth filtration. The formed deposit was removed using a 1 wt% solution of sodium hydroxide as a rinsing solution.

  3. Protein absorption and fouling on poly(acrylic acid)-graft-polypropylene microfiltration membrane

    Science.gov (United States)

    Liu, Yanjun; Ma, Huiying; Lv, Chunying; Yang, Jia; Fu, Xueqi

    2009-07-01

    A series of pH-sensitive poly (acrylic acid)-graft-polypropylene hollow fiber microfiltration membranes were prepared by UV-photo-irradiation. Bovine serum albumin (BSA) was chosen as the model protein to investigate its absorption and fouling behaviors on membranes. The results showed that the hydrophilicity of grafted membrane was improved by poly(acrylic acid) chains with parts of membrane pores blocked. The grafted membranes were markedly pH-dependent on the water permeability as pH was altered from 1 to 11. The zeta potential of grafted membranes calculated by streaming potential was negative in most pH range. Electrostatic interaction energy calculated by DLVO theory showed the electric interaction force between grafted membrane and BSA was attractive. With the rise of grafting degree, the electric attractive force between grafted membrane and BSA increased as pH=3 and decreased as pH=8, while it kept basically unchanged as pH=4.7. As a result, most serious fouling was observed as pH=4.7. Grafted membranes had a lower BSA absorption and better antifouling behavior as pH=8, while the opposite result was revealed as pH=3. In conclusion, the absorption and fouling behavior of BSA on membranes was pH-dependent due to the pH-dependence of membrane charge, and the conformation of BSA and grafting chains.

  4. Marine bacterial transparent exopolymer particles (TEP) and TEP precursors: Characterization and RO fouling potential

    KAUST Repository

    Li, Sheng

    2015-10-31

    This paper investigated the characteristics and membrane fouling potential of bacterial transparent exopolymer particles (TEP)/TEP precursors released from two marine bacteria, Pseudidiomarina homiensis (P. homiensis) and Pseudoalteromonas atlantica (P. atlantica), isolated from the Red Sea. Results showed that both bacteria grew at the similar rate, but the production of TEP/TEP precursors from P. atlantica was higher than that from P. homiensis. During the 168. h of incubation time, production rates of TEP/TEP precursors from P. atlantica and P. homiensis were 0.30 and 0.08 xanthan gum eq. mg/L-h, respectively. Isolated bacterial TEP precursors were mainly biopolymer, and P. atlantica produced a significantly higher concentration of biopolymer than that produced by P. homiensis. TEP/TEP precursors from both marine bacteria possessed protein-like material and were very similar in composition to previously reported foulants isolated from a fouled reverse osmosis (RO) membrane. Bacterial TEP/TEP precursors mostly consisted of aliphatic hydrocarbon from amino acids and amide group carbon of proteins (around 55%). Bacterial TEP precursors caused obvious fouling on RO membranes, which may create an ideal environment for bacteria attachment and promote to biofouling.

  5. Fouling Mechanisms of Humic Acid Membrane Fouling during Microfiltration Using xDLVO Approach%xDLVO 理论解析腐殖酸微滤膜污染机理

    Institute of Scientific and Technical Information of China (English)

    刘晓倩; 高欣玉; 梁爽; 张建

    2015-01-01

    运用 extended Derjaguin-Landau-Verwey-Overbeek (xDLVO)理论定量解析不同 pH值下腐殖酸微滤膜污染机理。理论计算表明,随着 pH 升高,膜污染趋势会降低,这主要是通过改变极性相互作用而实现的,并且过滤初期的膜污染比后期更严重。过滤实验验证了xDLVO 理论预测膜污染趋势的准确性。不同阶段下界面相互作用能和膜污染趋势的线性拟合表明,在粘附阶段膜污染趋势对界面作用能更敏感。%The mechanisms governing humic acid fouling of microfiltration membranes under diff-erent solution pHs were quantitatively analyzed using the extended Derjaguin-Landau-Verwey-Overbeek (xDLVO) approach. According to theoretical calculations, membrane fouling would bec-ome less severe at higher pH, which is mainly attributed to the change of acid-base interfacial in-teraction. Besides, membrane fouling would become more serious in the initial stage than that in the final stage. The validity of xDLVO approach for predicting the severity of membrane fouling was proved by the membrane fouling experimental results. Quantitative analysis of the relationship between fouling potential and interaction energy in different stages suggested that membrane fouling is more sensitive to the change of interfacial interaction in the adhesion stage than that in the cohesion stage.

  6. Fouling detection in buried water pipelines by observation of the scattered electromagnetic field

    Science.gov (United States)

    Frezza, Fabrizio; Mangini, Fabio; Santini, Carlo; Stoja, Endri; Tedeschi, Nicola

    2014-05-01

    The electromagnetic scattered field by a buried pipeline is calculated by means of frequency-domain numerical simulations and by making use of the scattered-field formulation. The pipeline, supposed to be used for water conveyance, is modeled as a cylindrical shell made of poly-vinyl chloride (PVC) material buried in a wall or pavement composed of cement with very low losses and filled with water. In order to make the model simpler, the pipeline is supposed running parallel to the air-cement interface. To excite the model, a linearly-polarized plane wave impinging normally on the above-mentioned interface is adopted. We consider two different polarizations in order to determine the most useful in terms of scattered-field sensitivity. Moreover, a preliminary frequency sweep allows us to choose the most suitable operating frequency depending on the dimensions of the pipeline cross-section. All the three components of the scattered field are monitored along a line just above the interface. The electromagnetic properties of the materials employed in this study are present in the literature and, since a frequency-domain technique is adopted, no further approximation is needed. Once the ideal problem has been studied, we further complicate the model by introducing two fouling scenarios due to limestone formation on the pipeline walls. In the first case, the fouling is deposited at the bottom of the pipeline when the water pressure is low enough and the second one considers the fouling to deposit on the entire internal perimeter of the pipeline's cross-section by forming an additional limestone cylindrical layer. The results obtained in these cases are compared with those of the initial problem with the goal of determining the scattered field dependency on the fouling geometrical characteristics. One of the practical applications in the field of Civil Engineering of this study may be the use of ground penetrating radar (GPR) techniques to monitor the fouling conditions of

  7. Nanoporous anti-fouling silicon membranes for biosensor applications.

    Science.gov (United States)

    Desai, T A; Hansford, D J; Leoni, L; Essenpreis, M; Ferrari, M

    2000-01-01

    The ability to create biocompatible well-controlled membranes has been an area of great interest over the last few years, particularly for biosensor applications. The present study describes the fabrication and characterization of novel nanoporous micromachined membranes that exhibit selective permeability and low biofouling. Results indicate that such membranes can be fabricated with uniform pore sizes capable of the simultaneous exclusion of albumin and diffusion of glucose. Compared to polymeric membranes of similar pore size, micromachined silicon membranes allowed more than twice the amount of glucose diffusion after 240 min and complete albumin exclusion. Moreover, membranes exhibit no morphological change or degradability in the presence of biological proteins and fluids at 37 degrees C. The results point to the potential of using such membranes for implantable biosensor applications. With monodisperse pores sizes as small as 10 nm, these membranes offer advantages in their reproducibility, stability, and ability to be integrated in silicon-based biosensing technology.

  8. Towards sustainable membrane filtration of palm oil mill effluent: analysis of fouling phenomena from a hybrid PAC-UF process

    Science.gov (United States)

    Amosa, Mutiu Kolade

    2016-10-01

    Sustainability of a membrane process depends on many factors of which fouling mitigation is the most central. Because membrane fouling phenomenon is very complex, extent of fouling potential of a feedwater with respect to a membrane has to be identified right from the design stage. This will acquaint engineers with the proper fouling mitigation measures during operation. This study presents a preliminary fouling data from the ultrafiltration of biotreated palm oil mill effluent (POME) after an upstream adsorption process. The flux decline is studied in a typical constant-pressure experiments with a cross-flow ultrafiltration of biotreated POME through Sartocon® polyethersulfone membranes (MWCOs 1, 5 and 10 kDa) at applied pressures of 40, 80 and 120 kPa. Results are examined, within the frame of the common blocking mechanisms and it was found that the blocking index η decreased from 2 to 0. Pore blocking phenomenon was successively observed from complete blocking (η = 2) down to cake filtration (η = 0), and the early blockage of the pores and a formation of a cake resulted in a limiting cake height. Thus, cake filtration could be best used to explain the fouling mechanisms of biotreated POME on the ultrafiltration membranes based on the R 2 values at all applied pressures. This demonstrates that the fouling was as a result of gradual reversible cake deposition which could easily be removed by less onerous cleaning methods. In addition, it could be concluded that the upstream adsorption reduced the particulate deposition on the membrane surface.

  9. The impact of fouling on the process performance of the thermal treatment of pig slurry using tubular heat exchangers.

    Science.gov (United States)

    Cunault, C; Burton, C H; Pourcher, A M

    2013-03-15

    The aim of this study was to determine the kinetics of fouling and their influence on the performance of a thermal treatment process used for sanitisation of pig slurry. Two temperatures (55 °C and 80 °C) were investigated. One trial was carried out at 55 °C and 80 °C in which the slurry was not re-circulated and one trial at 80 °C in which 100% or 50% of the slurry was re-circulated. Fouling of the heat exchangers was assessed by on-line monitoring of the drop in pressure, changes in treatment temperature, heat transfer coefficients, heat recycling rate, and energy consumption. Similar energy consumption of around 38 kWh m(-3) of effluent was observed at the two temperatures. The operating periods prior to excessive fouling or blockage were 18 days at 55 °C and four days at 80 °C. Recycling treated manure to obtain 50% dilution of the raw feed increased the viable operating period to 14 days at 80 °C but doubled energy consumption. At 55 °C, the significant drop in the target temperature (>7 °C) with fouling severely jeopardised the process. The nature of the decline in performance suggests that the main fouling mechanisms were bio-fouling at 55 °C and organic/mineral deposits at 80 °C. Recycling treated manure enabled the operating period to be extended but increased the total cost of heating. One hundred percent recycling showed that the fouling potential of the manure was largely eliminated after one thermal treatment, suggesting a pretreatment may be advantageous.

  10. Bioinspired Zwitterionic Surface Coatings with Robust Photostability and Fouling Resistance.

    Science.gov (United States)

    Huang, Chun-Jen; Chu, Sz-Hau; Wang, Lin-Chuan; Li, Chien-Hung; Lee, T Randall

    2015-10-28

    Great care has been paid to the biointerface between a bulk material and the biological environment, which plays a key role in the optimized performance of medical devices. In this work, we report a new superhydrophilic adsorbate, called L-cysteine betaine (Cys-b), having branched zwitterionic groups that give rise to surfaces and nanoparticles with enhanced chemical stability, biofouling resistance, and inertness to environmental changes. Cys-b was synthesized from the amphoteric sulfur-containing amino acid, L-cysteine (Cys), by quaternization of its amino group. Gold surfaces modified with Cys-b exhibited prominent repellence against the nonspecific adsorption of proteins, bacteria, and fibroblast cells. In addition, Cys-b existed in zwitterionic form over a wide pH range (i.e., pH 3.4 to 10.8), and showed excellent suppression in photoinduced oxidation on gold substrates. Furthermore, the modification of hollow Ag@Au nanoshells with Cys-b gave rise to nanoparticles with excellent colloidal stability and resistance to coordinative interaction with Cu(2+). Taken together, the unique features of Cys-b offer a new nanoscale coating for use in a wide spectrum of applications.

  11. Effect of Fouling Organisms on Food Uptake and Nutrient Release of Scallop (Chlamys nobilis, Reeve) Cultured in Daya Bay

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Biofouling is an important factor that affects the bivalve farming industry. Fouling organisms may reduce growth and survival rate of the cultured species. Fouler are often filter feeders, so they are potential competitors for food resource with the cultured species. The present study was conducted to measure the impact of fouling on food uptake and nutrient release in April and June, 2006 in Daya Bay near Guangzhou, China. Results showed that fouling organisms had significant effect on food uptake and nutrient release. The chlorophyll a uptake rate of fouled scallops was 7.53Lh-1±1.416Lh-1 and 11.94Lh-1±2.497Lh-1 in April and June, respectively, significantly higher than those of cleaned scallops, i.e., 4.23 Lh-1 ±2.744Lh-1 and 2.57Lh-1± 1.832 Lh-1 respectively.The consumption of total particulate matter by fouled scallops in April and June was 5.52Lh-1±0.818Lh-1 and 3.07Lh-1±0.971 Lh-1,respectively; the corresponding results for cleaned scallops are 2.49Lh-1 ±0.614Lh-1 and 2.37± 1.214Lh-1, respectively. Fouling increased ammonia release significantly. The ammonia release rate of fouled scallops was 33.81Lh-1±7.699Lh-1 and 76.39Lh-1 ±9.251Lh-1 in April and June, while cleaned scallops released 2.46Lh-1± 0.5 1 1Lh-1 and 7.23Lh-1± 1.026Lh-1 ammonia, respectively. Phosphate release of fouled scallops was 22.72Lh-1 ± 9.978 Lh-1 in June and cleaned scallops released phosphate 6.01Lh-1 ±0.876 Lh-1 in April. Therefore, fouling contributed much to food reduction and concentration increase of ammonia and phosphate in water.

  12. Characterization and anti-fouling performance of nano-Al₂O₃/PVDF membrane for Songhua river raw water filtration.

    Science.gov (United States)

    Yu, S L; Shi, W X; Lu, Y; Yang, J X

    2011-01-01

    Polyvinylidene fluoride (PVDF) flat ultrafiltration membranes modified by nano-sized alumina (Al₂O₃) particles were prepared by phase inversion process and their properties and anti-fouling performances were examined. The influence of three types of natural organic matters on the modified membrane fouling was also studied. Raw water was taken from two different locations, i.e., Harbin and Zhaoyuan, of Songhua River. Dissolved organic compounds in the raw water were fractionated using XAD resins into three fractions, i.e., hydrophobic fraction, transphilic fraction, and hydrophilic fraction (HPI). The three adsorbed compounds were further eluted and dissolved into distilled water respectively to prepare the feed for the fouling tests. All solutions were adjusted to a concentration of 10.6 mg C/L, which equals to the total organic carbon (TOC) of the raw water. Results show that the addition of nano-Al₂O₃ particulars did not affect the inherent traits of the PVDF membranes, however, its surface hydrophilic properties were improved significantly with the addition of nanoparticles and anti-fouling performance was enhanced as well. The HPIs in the Songhua River were the main foulant, causing more fouling to membrane than hydrophobic and transphilic matters.

  13. Influence of photo-induced superhydrophilicity of titanium dioxide nanoparticles on the anti-fouling performance of ultrafiltration membranes

    Science.gov (United States)

    Madaeni, S. S.; Ghaemi, N.; Alizadeh, A.; Joshaghani, M.

    2011-05-01

    Fouling is one of the most present prominent problems in almost all membrane processes. An increase in the membrane hydrophilicity is one of the effective ways to improve the membrane resistance to fouling. In this research, TiO 2 nanoparticles were deposited on the surface of composite ultrafiltration (UF) membrane, and then irradiated by ultraviolet (UV) light. The coating of the membrane surface with TiO 2 nanoparticles and radiation with (UV) light led to the considerable increase of hydrophilicity on the membrane surface. The deposition of TiO 2 nanoparticles was carried out through coordinance bonds with OH functional groups of the polymer on the membrane surface. The flux through a coated and (UV) light radiated membrane was increased to a large extent compared to a virgin membrane. In this research, the effect of different concentrations of TiO 2 nanoparticles in the presence and absence of (UV) irradiation was investigated, and the role of increasing of hydrophilicity on the anti-fouling property of membranes was studied. In order to characterize the membranes FTIR, XRD, SEM, water contact angle and cross-flow filtration were employed. This procedure is a useful technique for improvement of hydrophilicity to decrease (increase) fouling (anti-fouling performance) and enhance the permeation of membranes.

  14. Influence of photo-induced superhydrophilicity of titanium dioxide nanoparticles on the anti-fouling performance of ultrafiltration membranes

    Energy Technology Data Exchange (ETDEWEB)

    Madaeni, S.S., E-mail: smadaeni@yahoo.com [Membrane Research Center, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Ghaemi, N. [Membrane Research Center, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Department of Chemical Engineering, Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of); Alizadeh, A. [Nanoscience and Nanotechnology Research Centre (NNRC), Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Joshaghani, M. [Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of)

    2011-05-01

    Fouling is one of the most present prominent problems in almost all membrane processes. An increase in the membrane hydrophilicity is one of the effective ways to improve the membrane resistance to fouling. In this research, TiO{sub 2} nanoparticles were deposited on the surface of composite ultrafiltration (UF) membrane, and then irradiated by ultraviolet (UV) light. The coating of the membrane surface with TiO{sub 2} nanoparticles and radiation with (UV) light led to the considerable increase of hydrophilicity on the membrane surface. The deposition of TiO{sub 2} nanoparticles was carried out through coordinance bonds with OH functional groups of the polymer on the membrane surface. The flux through a coated and (UV) light radiated membrane was increased to a large extent compared to a virgin membrane. In this research, the effect of different concentrations of TiO{sub 2} nanoparticles in the presence and absence of (UV) irradiation was investigated, and the role of increasing of hydrophilicity on the anti-fouling property of membranes was studied. In order to characterize the membranes FTIR, XRD, SEM, water contact angle and cross-flow filtration were employed. This procedure is a useful technique for improvement of hydrophilicity to decrease (increase) fouling (anti-fouling performance) and enhance the permeation of membranes.

  15. Effect of temperature on extracellular organic matter (EOM) of Chlorella pyrenoidosa and effect of EOM on irreversible membrane fouling.

    Science.gov (United States)

    Zhao, Fangchao; Su, Yiming; Tan, Xiaobo; Chu, Huaqiang; Zhang, Yalei; Yang, Libin; Zhou, Xuefei

    2015-12-01

    Extracellular organic matter (EOM) can cause serious membrane fouling during the algae harvesting process. In this study, the secretion of EOM, including bound-EOM (bEOM) and dissolved-EOM (dEOM), by Chlorella pyrenoidosa (C. pyrenoidosa) at different culturing temperatures, and their influences on membrane filtration, have been investigated. The secretion of EOM was markedly reduced at high temperatures. The specific EOM secretion rate (SEOM) reached 831.1 ± 55.3mg/g at the lowest temperatures of 15 °C; in contrast, the SEOM decreased to only 370-442 and 356-406 mg/g with temperature rising above 20-25 and 30-35 °C, respectively. Based on membrane filtration experiments, the influence of EOM on irreversible membrane fouling was studied. In a critical flux experiment, low critical flux (24 L/m(2)h) was observed in a system with a high EOM concentration. The fouled membranes were rinsed by water and then used for continuous filtration, scanning electron microscope (SEM) analysis and fourier transform infrared spectroscopy (FTIR) analysis. The results revealed that there was irreversible membrane fouling caused by EOM, and irreversible membrane fouling can be more serious when an algae solution contains high EOM levels.

  16. Diminished swelling of cross-linked aromatic oligoamide surfaces revealing a new fouling mechanism of reverse-osmosis membranes.

    Science.gov (United States)

    Ying, Wang; Kumar, Rajender; Herzberg, Moshe; Kasher, Roni

    2015-06-02

    Swelling of the active layer of reverse osmosis (RO) membranes has an important effect on permeate water flux. The effects of organic- and biofouling on the swelling of the RO membrane active layer and the consequent changes of permeate flux are examined here. A cross-linked aromatic oligoamide film that mimics the surface chemistry of an RO polyamide membrane was synthesized stepwise on gold-coated surfaces. Foulant adsorption to the oligoamide film and its swelling were measured with a quartz crystal microbalance, and the effects of fouling on the membrane's performance were evaluated. The foulants were extracellular polymeric substances (EPS) extracted from fouled RO membranes and organic compounds of ultrafiltration permeate (UFP) from a membrane bioreactor used to treat municipal wastewater. The adsorbed foulants affected the swelling of the cross-linked oligoamide film differently. EPS had little effect on the swelling of the oligoamide film, whereas UFP significantly impaired swelling. Permeate flux declined more rapidly under UFP fouling than it did under EPS. Foulant adsorption was shown to diminish swelling of the aromatic oligoamide surfaces. Among the already known RO membrane fouling mechanisms, a novel RO fouling mechanism is proposed, in which foulant-membrane interactions hinder membrane swelling and thus increase hydraulic resistance.

  17. Enhanced tubes for steam condensers. Volume 1, Summary of condensation and fouling; Volume 2, Detailed study of steam condensation

    Energy Technology Data Exchange (ETDEWEB)

    Webb, R.L.; Chamra, L.; Jaber, H.

    1992-02-01

    Electric utility steam condensers typically use plain tubes made of titanium, stainless steel, or copper alloys. Approximately two-thirds of the total thermal resistance is on the water side of the plain tube. This program seeks to conceive and develop a tube geometry that has special enhancement geometries on the tube (water) side and the steam (shell) side. This ``enhanced`` tube geometry, will provide increased heat transfer coefficients. The enhanced tubes will allow the steam to condense at a lower temperature. The reduced condensing temperature will reduce the turbine heat rate, and increase the plant peak load capability. Water side fouling and fouling control is a very important consideration affecting the choice of the tube side enhancement. Hence, we have consciously considered fouling potential in our selection of the tube side surface geometry. Using appropriate correlations and theoretical models, we have designed condensation and water side surface geometries that will provide high performance and be cleanable using sponge ball cleaning. Commercial tube manufacturers have made the required tube geometries for test purposes. The heat transfer test program includes measurement of the condensation and water side heat transfer coefficients. Fouling tests are being run to measure the waterside fouling resistance, and to the test the ability of the sponge ball cleaning system to clean the tubes.

  18. Effect of membrane polymeric materials on relationship between surface pore size and membrane fouling in membrane bioreactors

    Science.gov (United States)

    Miyoshi, Taro; Yuasa, Kotaku; Ishigami, Toru; Rajabzadeh, Saeid; Kamio, Eiji; Ohmukai, Yoshikage; Saeki, Daisuke; Ni, Jinren; Matsuyama, Hideto

    2015-03-01

    We investigated the effect of different membrane polymeric materials on the relationship between membrane pore size and development of membrane fouling in a membrane bioreactor (MBR). Membranes with different pore sizes were prepared using three different polymeric materials, cellulose acetate butyrate (CAB), polyvinyl butyral (PVB), and polyvinylidene fluoride (PVDF), and the development of membrane fouling in each membrane was evaluated by batch filtration tests using a mixed liquor suspension obtained from a laboratory-scale MBR. The results revealed that the optimal membrane pore size to mitigate membrane fouling differed depending on membrane polymeric material. For PVDF membranes, the degree of membrane fouling decreased as membrane pore size increased. In contrast, CAB membranes with smaller pores had less fouling propensity than those with larger ones. Such difference can be attributed to the difference in major membrane foulants in each membrane; in PVDF, they were small colloids or dissolved organics in which proteins are abundant, and in CAB, microbial flocs. The results obtained in this study strongly suggested that optimum operating conditions of MBRs differ depending on the characteristics of the used membrane.

  19. Effect of processing parameters on fouling resistances during microfiltration of red plum and watermelon juices: a comparative study.

    Science.gov (United States)

    Nourbakhsh, Himan; Alemi, Azam; Emam-Djomeh, Zahra; Mirsaeedghazi, Hossein

    2014-01-01

    This study evaluated the total (R t ), reversible (R rev ), irreversible (R irr ), and cake (R c ) resistances during microfiltration of watermelon juice (as a juice with colloid particles) and red plum juice (as a juice without colloid particles). Results showed that the total resistance decreased by about 45% when the feed velocity was increased during clarification of red plum juice due to change in cake resistance. Also, increasing the feed temperature from 20 to 30°C decreased the total fouling resistance by about 9% due to decreases in the irreversible and reversible fouling resistances. Also, mixed cellulose ester (MCE) membrane (which is hydrophilic) had a lower cake resistance compared to polyvinylidene fluoride (PVDF) membrane (which is hydrophobic). Examination of the microfiltration of watermelon juice showed that R t decreased by about 54% when the feed temperature was increased from 20 to 50°C, partially due to the reduction of reversible fouling resistance by 78%. Also, increasing transmembrane pressures from 0.5 to 2.5 bars greatly increased total fouling resistance. The feed velocity had a different effect on fouling resistances during microfiltration of watermelon juice compared to red plum juice: in contrast with red plum juice, increasing the feed velocity for watermelon juice increased cake resistance.

  20. Filtering Surface Water with a Polyurethane-based Hollow Fiber Membrane:Effects of Operating Pressure on Membrane Fouling

    Institute of Scientific and Technical Information of China (English)

    赵学辉; 张宏伟; 王捷

    2014-01-01

    Membrane fouling seriously restricts applications of membrane technology. A novel strategy was ap-plied in this study to retard membrane fouling by changing operating pressure with the pressure responsibility membrane. A polyurethane-based hollow fiber membrane was used to treat surface water for evaluating the effect of operating pressure on membrane fouling. Some bench-scale tests in dead-end mode were carried out. In the experi-ments without backwashing, as operating pressure increased, severe membrane fouling occurred on membrane sur-face, while the permeate quality was improved obviously, which is considered to be due to shrinkage deformation. The total resistance, irreversible resistance and reversible resistance under different backwash pressures were de-termined in filtration/backwashing test. With the increase of backwash pressure, the total resistance decreased, and more importantly, the irreversible resistance also decreased, which implies that small particles deposited inside membrane pores and cake layers on membrane surface are effectively removed. Similar results could be obtained in mass balance tests. The results of the present study indicate that the application of pressure responsibility membrane in surface water treatment may be an effective strategy for reducing membrane fouling.

  1. An atomic force microscopy study on fouling characteristics of modified PES membrane in submerged membrane bioreactor for domestic wastewater treatment

    Science.gov (United States)

    Liu, Shuo; Han, Hongjun; Liu, Yanping; Wang, Baozhen

    2008-10-01

    To investigate the fouling characteristics of modified PES membrane in submerged Membrane Bioreactor (MBR) for domestic wastewater treatment, Atomic Force Microscope (AFM) study was conducted to analyze the microstructure characteristics of PES membrane. Surface roughness and section analysis of both virgin and fouled membrane were achieved by software of NanoScope 6.12. Compared to the virgin membrane, the average roughness (Ra), square average roughness (Rms) and ten points average roughness (Rz) of fouled membrane were increased by 100.6nm, 133.7nm and 330.7nm respectively. The section analysis results indicated that the cake layer formed and membrane pore blocked were the main causes for the increase of TMP. Micro-filtration resistance analysis was conducted to support the results of AFM analysis. It is showed that membrane resistance, cake resistance, pore blocking and irreversible fouling resistance is 0.755, 1.721 and 1.386 respectively, which contributed 20%, 44%, and 36%, respectively, to total resistance of submerged MBR (at MLSS 6000mg/L and flux 21.9L/m2Â.h). The results proved that AFM could be used to properly describe the fouling characteristics of modified PES membrane in submerged MBR through roughness and section analysis.

  2. Full-scale simulation of seawater reverse osmosis desalination processes for boron removal: Effect of membrane fouling.

    Science.gov (United States)

    Park, Pyung-Kyu; Lee, Sangho; Cho, Jae-Seok; Kim, Jae-Hong

    2012-08-01

    The objective of this study is to further develop previously reported mechanistic predictive model that simulates boron removal in full-scale seawater reverse osmosis (RO) desalination processes to take into account the effect of membrane fouling. Decrease of boron removal and reduction in water production rate by membrane fouling due to enhanced concentration polarization were simulated as a decrease in solute mass transfer coefficient in boundary layer on membrane surface. Various design and operating options under fouling condition were examined including single- versus double-pass configurations, different number of RO elements per vessel, use of RO membranes with enhanced boron rejection, and pH adjustment. These options were quantitatively compared by normalizing the performance of the system in terms of E(min), the minimum energy costs per product water. Simulation results suggested that most viable options to enhance boron rejection among those tested in this study include: i) minimizing fouling, ii) exchanging the existing SWRO elements to boron-specific ones, and iii) increasing pH in the second pass. The model developed in this study is expected to help design and optimization of the RO processes to achieve the target boron removal at target water recovery under realistic conditions where membrane fouling occurs during operation.

  3. Characteristics and composition of fouling caused by pig slurry in a tubular heat exchanger--recommended cleaning systems.

    Science.gov (United States)

    Cunault, C; Coquinot, Y; Burton, C H; Picard, S; Pourcher, A M

    2013-03-15

    The structure and composition of the fouling deposits caused by pig slurry heated in a tubular heat exchanger were characterized to understand their formation and thus be able to minimize fouling and define effective routine cleaning methods. Two temperatures (55 °C and 80 °C) were investigated. Two types of fouling were identified: organic/mineral and biofilm. The first only formed at temperatures above 50 °C, often during the heating phase, and was the main problem encountered in treatments at 80 °C. Organic/mineral deposits formed a thin compact sub-layer and a thick porous top layer composed of 67-76% minerals, 9-15% proteins, 8-20% carbohydrates and 0-5% fats. Biofilms formed at temperatures between 25 °C and 70 °C in both the cooling and heating sections of the exchanger. This type of fouling predominated at temperatures below 55 °C. The biofilm covered a thin mineral base layer. Strongly acidic or alkaline washing cycle are recommended to clean Type I deposits, while in-line gas-rumbling is recommended for Type II fouling.

  4. Environmentally benign sol-gel antifouling and foul-releasing coatings.

    Science.gov (United States)

    Detty, Michael R; Ciriminna, Rosaria; Bright, Frank V; Pagliaro, Mario

    2014-02-18

    Biofouling on ships and boats, characterized by aquatic bacteria and small organisms attaching to the hull, is an important global issue, since over 80000 tons of antifouling paint is used annually. This biofilm, which can form in as little as 48 hours depending on water temperature, increases drag on watercraft, which greatly reduces their fuel efficiency. In addition, biofouling can lead to microbially induced corrosion (MIC) due to H2S formed by the bacteria, especially sulfate-reducing bacteria. When the International Maritime Organization (IMO) international convention banned the use of effective but environmentally damaging coatings containing tributyl tin in 2008, the development of clean and effective antifouling systems became more important than ever. New nonbiocidal coatings are now in high demand. Scientists have developed new polymers, materials, and biocides, including new elastomeric coatings that they have obtained by improving the original silicone (polydimethylsiloxane) formulation patented in 1975. However, the high cost of silicones, especially of fluoropolymer-modified silicones, has generally prevented their large-scale diffusion. In 2009, traditional antifouling coatings using cuprous oxide formulated in copolymer paints still represented 95% of the global market volume of anti-fouling paints. The sol-gel nanochemistry approach to functional materials has emerged as an attractive candidate for creating low fouling surfaces due to the unique structure and properties of silica-based coatings and of hybrid inorganic-organic silicas in particular. Sol-gel formulations easily bind to all types of surfaces, such as steel, fiberglass, aluminum, and wood. In addition, they can cure at room temperature and form thin glassy coatings that are markedly different from thick silicone elastomeric foul-releasing coatings. Good to excellent performance against biofouling, low cure temperatures, enhanced and prolonged chemical and physical stability, ease of

  5. EDTA fouling in dead-end ultrafiltration of low level radioactive wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Lixia [Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (MARC), Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055 (China); Zhang, Xue [Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Zhao, Xuan, E-mail: zhxinet@mail.tsinghua.edu.cn [Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Hu, Hongying [Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084 (China); State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (MARC), Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055 (China)

    2015-12-15

    Highlights: • EDTA in LLRW caused unrecoverable UF membrane fouling. • The rejection of nuclides by UF was significantly enhanced with EDTA addition. • The nuclide (except Ag) deposition on membrane increased with EDTA addition. • Reducing EDTA in the feed water or alkaline/ultrasonic washing were suggested. - Abstract: EDTA is widely used as a detergent, and finally enters into wastewater. The influence of EDTA on ultrafiltration of low level radioactive wastewater (LLRW) was investigated under different operation conditions. As the main organic pollutant, EDTA led to unrecoverable membrane fouling and the normalized flux decreased from 100% to 85% depending on its concentration. The clogging caused by EDTA increased the surface roughness of the membrane, leading to the flux reduction. Both nuclide rejections and depositions on the membrane surfaces were enhanced with EDTA addition, due to the strong complexation of the nuclides with EDTA. However, Ag deposition on the membrane decreased slightly in the presence of EDTA, which may be caused by the stronger attraction of Ag to the unmodified membrane than that to the EDTA-modified one. Transmembrane pressure (TMP) and molecular weight cut off (MWCO) of membranes had negligible effects on membrane fouling, while the nuclide rejections by membrane and the depositions of nuclides on membrane both decreased significantly when the TMP increased to 0.2 MPa and MWCO increased from 5 kDa to 30 kDa. Based on these results, it clearly showed that EDTA even at a low concentration had strong effects on the performance of UF treating LLRW. Therefore, it is suggested for industrial application that pretreatments to reduce EDTA or alkaline/ultrasonic washing involved in UF process were necessary to reduce the nuclide depositions on the membrane surfaces and irradiation dose of membrane surface.

  6. Role of monomer sequence and backbone structure in polypeptoid and polypeptide polymers for anti-fouling applications

    Science.gov (United States)

    Patterson, Anastasia; Rizis, Georgios; Wenning, Brandon; Finlay, John; Ober, Christopher; Segalman, Rachel

    Polymeric coatings rely on a fine balance of surface properties to achieve biofouling resistance. Bioinsipired polymers and oligomers provide a modular strategy for the inclusion of multiple functionalities with controlled architecture, sequence and surface properties. In this work, polypeptoid and polypeptide functionalized coatings based on PEO and PDMS block copolymers were compared with respect to surface presentation and fouling by Ulva linza. While polypeptoids and polypeptides are simple isomers of each other, the lack of backbone chirality and hydrogen bonding in polypeptoids leads to surprisingly different surface behavior. Specifically, the polypeptoids surface segregate much more strongly than analogous polypeptide functionalized polymers, which in turn affects the performance of the coating. Indeed, polypeptoid functionalized surfaces were significantly better both in terms of anti-fouling and fouling release than the corresponding polypeptide-bearing polymers. The role of specific monomer sequence and backbone chemistry will be further discussed in this poster.

  7. Flexible Design and Operation of Multi-Stage Flash (MSF Desalination Process Subject to Variable Fouling and Variable Freshwater Demand

    Directory of Open Access Journals (Sweden)

    Said Alforjani Said

    2013-10-01

    Full Text Available This work describes how the design and operation parameters of the Multi-Stage Flash (MSF desalination process are optimised when the process is subject to variation in seawater temperature, fouling and freshwater demand throughout the day. A simple polynomial based dynamic seawater temperature and variable freshwater demand correlations are developed based on actual data which are incorporated in the MSF mathematical model using gPROMS models builder 3.0.3. In addition, a fouling model based on stage temperature is considered. The fouling and the effect of noncondensable gases are incorporated into the calculation of overall heat transfer co-efficient for condensers. Finally, an optimisation problem is developed where the total daily operating cost of the MSF process is minimised by optimising the design (no of stages and the operating (seawater rejected flowrate and brine recycle flowrate parameters.

  8. The fouling of fish farm cage nets as bioindicator of aquaculture pollution in the Adriatic Sea (Croatia).

    Science.gov (United States)

    Sliskovic, Merica; Jelic-Mrcelic, Gorana; Antolic, Boris; Anicic, Ivica

    2011-02-01

    A fouling assemblage (including density, species richness and diversity, and biomass) growing on netting of fish farm cages was investigated in Stracinska Bay--Location 1 and Peles Bay--Location 2 (Croatia) in order to test the efficiency of fouling as a bioindicator of organic pollution. A total number of 40 algal taxa in Location 1 and total number of 22 algal taxa in Location 2 were identified, with a dominance of opportunistic species (ESG II). We found domination of algal species over animal species and absolute dominance of Rhodophyta which are typical fouler in the Adriatic Sea. Low diversity and species richness with increase in value of the R/P index (occasionally higher than 6) were recorded in Location 2, indicating a certain impact of nutrient enrichment from fish culture facilities on a fouling community structure.

  9. A conceptual model for the understanding of fouling phenomenon when using triazine based H2S scavengers

    DEFF Research Database (Denmark)

    Madsen, Henrik Tækker; Søgaard, Erik Gydesen; Jensen, Carina;

    2013-01-01

    The use of triazine based H2S scavengers is known to lead to formation of fouling that may cause significant problems during oil and gas production. The fouling has been found to originate from dithiazine produced during the reaction between the triazine and H2S. When using 1,3,5-tri-(2...... studied the applicability of the previously suggested model to describe the reaction between 1,3,5-tri-(2-hydroxypropyl)-hexahydro-s-triazine and H2S. To investigate the reaction system, electrospray ionization mass spectrometry (ESI-MS) has been employed to analyse the composition of the generated...... mixture as H2S is bubbled through the scavenger. The results of the study have confirmed that the suggested model is capable of explaining how the scavenger reacts with H2S, which may be used to explain from where and how the fouling originates, and how a scavenging process can be designed to avoid...

  10. Investigation of Filtration Membranes from the Dairy Protein Industry for Residual Fouling Using Infrared Spectroscopy and Chemometrics

    DEFF Research Database (Denmark)

    Jensen, Jannie Krog

    the result showed that the MCR model needed three factors to describe the system, one describing the membrane material (polyethersulfone, PES), and two describing the residual fouling that is present on the membrane. The MCR method improved the interpretation of the models considerably compared to e.g. PCA...... or the univariate data analysis. However, it also became evident that the penetration depth of the infrared beam creates additional complexity when measuring semi-solid layered samples. In order to obtain an overview of the different analysis methods and data analysis methods that have been employed by other...... how the application of multivariate infrared spectroscopy combined with new data analysis methods has augmented the knowledge about residual fouling on real size production membranes. The information obtained can be used to investigate and monitor residual membrane fouling and help in the design...

  11. Toxicity of anti-fouling biocides to Parorchis acanthus (Digenea: Philophthalmidae) cercarial encystment.

    Science.gov (United States)

    Morley, N J; Leung, K M Y; Morritt, D; Crane, M

    2003-03-17

    The toxicity of the anti-fouling biocides tributyltin (TBTO), copper, and Irgarol 1051 (irgarol) at nominal concentrations ranging from 10 to 10,000 microg l(-1) was investigated against the speed of encystment and successful formation of a protective cyst of the cercariae of Parorchis acanthus. For all biocide exposures, cercariae had a much slower rate of encystment and reduced cyst formation than controls. Exposure of the snail host Nucella lapillus for 7 d caused complete cessation of cercarial shedding in irgarol-exposed snails but had no effect on cercarial encystment from TBTO and copper-exposed snails. The mechanisms of toxicity of the biocides are briefly discussed.

  12. Use of thiolated oligonucleotides as anti-fouling diluents in electrochemical peptide-based sensors.

    Science.gov (United States)

    McQuistan, Adam; Zaitouna, Anita J; Echeverria, Elena; Lai, Rebecca Y

    2014-05-11

    We incorporated short thiolated oligonucleotides as passivating diluents in the fabrication of electrochemical peptide-based (E-PB) sensors, with the goal of creating a negatively charged layer capable of resisting non-specific adsorption of matrix contaminants. The E-PB HIV sensors fabricated using these diluents were found to be more specific and selective, while retaining attributes similar to the sensor fabricated without these diluents. Overall, these results highlight the advantages of using oligonucleotides as anti-fouling diluents in self-assembled monolayer-based sensors.

  13. Method for predicting fouling tendency of a hydrocarbon-containing feedstock

    Science.gov (United States)

    Schabron, John F; Rovani, Jr., Joseph F

    2013-07-23

    Disclosed herein is a method involving the steps of (a) precipitating an amount of asphaltenes from a liquid sample of a first hydrocarbon-containing feedstock having solvated asphaltenes therein with one or more first solvents in a column; (b) determining one or more solubility characteristics of the precipitated asphaltenes; (c) analyzing the one or more solubility characteristics of the precipitated asphaltenes; and (d) correlating a measurement of feedstock fouling tendency for the first hydrocarbon-containing feedstock sample with a mathematical parameter derived from the results of analyzing the one or more solubility characteristics of the precipitated asphaltenes.

  14. Early warning of diarrhea and pen fouling in growing pigs using sensor-based monitoring

    DEFF Research Database (Denmark)

    Jensen, D. B.; Toft, N.; Kristensen, A. R.

    Introduction: Today, pig farmers typically asses the health of their pigs while walking through their herd as part of the daily routine. In modern pig production, however, a herd will consists of thousands of pigs in a few hundred pens. If a farmer were to spend just two minutes observing each pen...... positions per pen (hourly), water flow per double-pen (liters/hour/pig) and drinking frequency per pen (activations/hour/pig). Staff registrations of diarrhea and pen fouling were the events of interest. The data were divided into a learning set (15 events) and a test set (18 events). The data were modeled...

  15. Low-Fouling Antibacterial Reverse Osmosis Membranes via Surface Grafting of Graphene Oxide.

    Science.gov (United States)

    Huang, Xinwei; Marsh, Kristofer L; McVerry, Brian T; Hoek, Eric M V; Kaner, Richard B

    2016-06-15

    Azide-functionalized graphene oxide (AGO) was covalently anchored onto commercial reverse osmosis (RO) membrane surfaces via azide photochemistry. Surface modification was carried out by coating the RO membrane with an aqueous dispersion of AGO followed by UV exposure under ambient conditions. This simple process produces a hydrophilic, smooth, antibacterial membrane with limited reduction in water permeability or salt selectivity. The GO-RO membrane exhibited a 17-fold reduction in biofouling after 24 h of Escherichia coli contact and almost 2 times reduced BSA fouling after a 1 week cross-flow test compared to its unmodified counterpart.

  16. Practical experience of backwashing with SWRO permeate for UF fouling control

    KAUST Repository

    Li, Sheng

    2013-01-01

    Effectiveness of seawater reverse osmosis (SWRO) permeate backwash on fouling control of seawater ultrafiltration was investigated at a pilot scale. A standard membrane module was used in this pilot to represent full-scale desalination plants. Results of the pilot show a good reproducibility. When the UF permeate was used for backwash, the frequency of chemically enhanced backwash (CEB) was around once per day. However, results of the pilot show that SWRO permeate backwashing could significantly reduce the CEB frequency. © 2013 Desalination Publications.

  17. Fouling mitigation in membrane distillation processes during ammonia stripping from pig manure

    DEFF Research Database (Denmark)

    Zarebska, Agata; Amor, Angel Cid; Ciurkot, Klaudia

    2015-01-01

    . This study investigates preliminary fouling of polypropylene (PP) and polytetrafluoroethylene (PTFE) membranes. A model manure solution was used as feed. In addition cleaning efficiencies with deionized water, NaOH/citric acid, and Novadan agents were studied. Further microfiltration and ultrafiltration were...... additionally contained carboxylates, free fatty acids and lignin. Among the tested cleaning strategies, Novadan agents were the most successful in removing proteins and carbohydrates from the PTFE membrane while it only removed proteins from the PP membrane. Using microfiltration or ultrafiltration...... as a pretreatment prior to MD doubled the ammonia mass transfer coefficient for the PTFE membrane, while for the PP membrane, the ammonia mass transfer coefficient was increased 4-fold....

  18. 基于冯·卡门类比的强化管污垢模型及抗垢机理%Fouling model of enhanced tubes based on von Karman analogy and anti-fouling mechanism

    Institute of Scientific and Technical Information of China (English)

    张仲彬; 李煜; 徐志明

    2012-01-01

    The comparative experiments on the CaCO3 fouling characteristics of four enhanced tubes (including the corrugated tube, convergent-divergent tube I , convergent-divergent tube II and arc-line tube) and a plain tube under the same operating conditions, such as the inlet temperature, flow velocity and hardness of artificial hard water and bath temperature of tubes, were carried out. Based on the von Karman analogy, ψ and ψ were regarded as their performance evaluation factors of heat transfer, ηψ and ηψ were used as their comprehensive performance evaluation indexes, and then a fouling model of enhanced tubes was established through the analysis of experimental data, such as their fouling resistance Rf and geometric parameters. The anti-fouling mechanisms of each enhanced tube were analyzed. The results show that it is the secondary turbulence and periodic pulse along the axis of flow velocity direction in the corrugated tube scouring near-wall flow that enhances the removal mass rate of fouling dramatically so that it is difficult for the tube to cause fouling and even realize automatic cleaning. The arc-line tube has the anti-fouling performance in which the periodic disturbance of flow in it weakens fouling deposition and the sharp increasing laryngeal wall shear stress boosting fouling removes greatly. The convergent-divergent tube can resist fouling because the fouling removal mass rate is enhanced doubly by fluid's intensive periodic disturbance caused by the alternate switch of axis pressure gradient and the swing eddy current at the laryngeal.%对比实验研究4种强化管(波纹管、缩放管Ⅰ、缩放管Ⅱ和弧线管)和光管在相同工况(人工硬水入口温度、流速、硬度及水浴温度)下的CaCO3污垢特性.通过分析强化管污垢热阻Rf与几何参数等,基于冯·卡门类比法,以ψ和ψ为强化管传热性能评价因子,η(Ψ)和η(ψ)为其综合性能评价指标,构建强化管污垢数据分析模型,并逐一

  19. Trypsin-enabled construction of anti-fouling and self-cleaning polyethersulfone membrane.

    Science.gov (United States)

    Shi, Qing; Su, Yanlei; Ning, Xue; Chen, Wenjuan; Peng, Jinming; Jiang, Zhongyi

    2011-01-01

    Constructing anti-fouling and self-cleaning membrane surfaces based on covalent attachment of trypsin on poly(methacrylic acid)-graft-polyethersulfone (PMAA-g-PES) membrane was reported. The carboxylic acid groups enriched on asymmetric PMAA-g-PES membrane surface were activated with 1-ethyl-(3-3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) and employed as chemical anchors for the conjugation with amino groups of trypsin. Activity assays showed that such chemically immobilized trypsin was much more active and stable than that of the physically adsorbed counterpart. Trypsin covalently attached on membrane surface could substantially resist protein fouling in dynamic flow process. The considerable enhancement of protein solution permeation flux was observed as a consequence of rapid enzymatic degradation of protein deposited onto membrane surface. The permeation flux of the membrane could be recovered upon simple hydraulic flush after protein filtration, suggesting superior self-cleaning property. After multi-cycle BSA filtration over 15-day period, the active self-cleaning membrane maintained more than 95.0% of its initial flux.

  20. Effects of membrane orientation on fouling characteristics of forward osmosis membrane in concentration of microalgae culture.

    Science.gov (United States)

    Honda, Ryo; Rukapan, Weerapong; Komura, Hitomi; Teraoka, Yuta; Noguchi, Mana; Hoek, Eric M V

    2015-12-01

    Application of forward osmosis (FO) membrane to microalgae cultivation processes enables concentration of microalgae and nutrients with low energy consumption. To understand fouling characteristics of FO membrane in concentration of microalgae culture, we studied flux decline, flux recovery by cleaning, and foulants characteristics, in different membrane orientation of active-layer-facing-feed-solution (AL-FS) and active-layer-facing-draw-solution (AL-DS) modes. Batch concentration of Chlorella vulgaris was conducted with a cellulose-triacetate FO membrane. Rapid flux decline and lower flux recovery was observed in AL-DS mode because of inner-membrane fouling including internal pore clogging, adsorption and internal concentration polarization in the support layer. A proportion of polysaccharides in extracellular polymeric substances to soluble microbial products were larger in chemical cleaning effluent than physical one in AL-DS mode, although those were not significantly different in AL-FS mode. Excitation-emission matrix analysis revealed that proteins and humic-like substances were also possible irreversible foulants both in AL-DS and AL-FS modes.

  1. Cross-sectional analysis of fouled SWRO membranes by STEM-EDS

    KAUST Repository

    Aubry, Cyril

    2014-01-01

    The intact cross-section of two fouled reverse osmosis membranes was characterized using a scanning transmission electron microscope (STEM) equipped with an electron energy dispersive spectroscope (EDS). Focused ion beam (FIB) was used to prepare a thin lamella of each membrane. These lamellas were then attached to a TEM grid for further STEM/EDS analysis. The foulant in sample A was mainly inorganic in nature and predominantly composed of alumino-silicate particles. These particles were surrounded by carbon at high concentrations, indicating the presence of organic materials. Iron was diffusely present in the cake layer and this could have enhanced the fouling process. The cake layer of membrane B was mainly consisted of organic matter (C, O, and N representing 95% of the total elemental composition) and organized in thin parallel layers. Small concentrations of Si, F, Na, Mg, and Cl were detected inside the active layer and support layer of the membrane. Due to the high sensitivity of the cake layer of membrane A to the electron beam, STEM/EDS line analyses might have been performed on large areas. On the other hand, the cake layer of sample B was resistant to the electron beam and the resolution of STEM/EDS was gradually improved until obtaining a resolution of 25. nm. © 2013 Elsevier B.V.

  2. Membrane fouling in a membrane bioreactor: High filtration resistance of gel layer and its underlying mechanism.

    Science.gov (United States)

    Chen, Jianrong; Zhang, Meijia; Li, Fengquan; Qian, Lei; Lin, Hongjun; Yang, Lining; Wu, Xilin; Zhou, Xiaoling; He, Yiming; Liao, Bao-Qiang

    2016-10-01

    A membrane bioreactor (MBR) was continuously operated to investigate mechanisms of fouling caused by the gel layer in this study. Agar was used as a model foulant for gel layer formation, and filtration resistance of gel layers was systematically assessed. The results showed that gel layer possessed unusually high specific filtration resistance (SFR) and high measured porosity as compared with cake layer. Current knowledge cannot explain the contradiction between high filtration resistance and high porosity of gel layer. A new fouling mechanism based on Flory-Huggins theory was then proposed. Filtration resistance of agar gel layer was found to be independent of pH and ionic strength, but linearly increase with gel thickness. The results are accordant with the mechanism deductions. Simulation of the mechanism model showed that the filtration resistance induced by mixing chemical potential variation was comparable to the experimental data of filtration resistance of agar gel layer, indicating that the proposed mechanism is the predominant mechanism responsible for the high filtration resistance of gel layer. The proposed mechanism was further verified from the bound water viewpoint.

  3. Chemical cleaning of fouled PVC membrane during ultrafiltration of algal-rich water

    Institute of Scientific and Technical Information of China (English)

    Yan Zhang; Jiayu Tian; Heng Liang; Jun Nan; Zhonglin Chen; Guibai Li

    2011-01-01

    Cleaning of hollow-fibre polyvinyl chloride (PVC) membrane with different chemical reagents after ultrafiltration of algal-rich water was investigated. Among the tested cleaning reagents (NaOH, HCl, EDTA, and NaClO), 100 mg/L NaClO exhibited the best performance (88.4% ± 1.1%) in removing the irreversible fouling resistance. This might be attributed to the fact that NaClO could eliminate almost all the major foulants such as carbohydrate-like and protein-like materials on the membrane surface, as confirmed by Fourier transform infrared spectroscopy analysis. However, negligible irreversible resistance (1.5% ± 1.0%) was obtained when the membrane was cleaning by 500 mg/L NaOH for 1.0 hr, although the NaOH solution could also desorb a portion of the major foulants from the fouled PVC membrane. Scanning electronic microscopy and atomic force microscopy analyses demonstrated that 500 mg/L NaOH could change the structure of the residual foulants on the membrane, making them more tightly attached to the membrane surface. This phenomenon might be responsible for the negligible membrane permeability restoration after NaOH cleaning. On the other hand, the microscopic analyses reflected that NaClO could effectively remove the foulants accumulated on the membrane surface.

  4. Natural Organic Matter Removal and Fouling in a Low Pressure Hybrid Membrane Systems

    Directory of Open Access Journals (Sweden)

    Vedat Uyak

    2014-01-01

    Full Text Available The objective of this study was to investigate powdered activated carbon (PAC contribution to natural organic matter (NOM removal by a submerged MF and UF hybrid systems. It was found that filtration of surface waters by a bare MF and UF membranes removed negligible TOC; by contrast, significant amounts of TOC were removed when daily added PAC particles were predeposited on the membrane surfaces. These results support the assumption that the membranes surface properties and PAC layer structure might have considerably influential factor on NOM removal. Moreover, it was concluded that the dominant removal mechanism of hybrid membrane system is adsorption of NOM within PAC layer rather than size exclusion of NOM by both of membrane pores. Transmembrane pressure (TMP increases with PAC membrane systems support the view that PAC adsorption pretreatment will not prevent the development of membrane pressure; on the contrary, PAC particles themselves caused membrane fouling by blocking the entrance of pores of MF and UF membranes. Although all three source waters have similar HPI content, it appears that the PAC interaction with the entrance of membrane pores was responsible for offsetting the NOM fractional effects on membrane fouling for these source waters.

  5. Flux recovery of ceramic tubular membranes fouled with whey proteins: Some aspects of membrane cleaning

    Directory of Open Access Journals (Sweden)

    Popović Svetlana S.

    2008-01-01

    Full Text Available Efficiency of membrane processes is greatly affected by the flux reduction due to the deposits formation at the surface and/or in the pores of the membrane. Efficiency of membrane processes is affected by cleaning procedure applied to regenerate flux. In this work, flux recovery of ceramic tubular membranes with 50 and 200 nm pore size was investigated. The membranes were fouled with reconstituted whey solution for 1 hour. After that, the membranes were rinsed with clean water and then cleaned with sodium hydroxide solutions or formulated detergents (combination of P3 Ultrasil 67 and P3 Ultrasil 69. Flux recovery after the rinsing step was not satisfactory although fouling resistance reduction was significant so that chemical cleaning was necessary. In the case of 50 nm membrane total flux recovery was achieved after cleaning with 1.0% (w/w sodium hydroxide solution. In the case of 200 nm membrane total flux recovery was not achieved irrespective of the cleaning agent choice and concentration. Cleaning with commercial detergent was less efficient than cleaning with the sodium hydroxide solution.

  6. Structure-performance-fouling studies of polysulfone microfiltration hollow fibre membranes

    Indian Academy of Sciences (India)

    P S Singh; K Parashuram; S Maurya; P Ray; A V R Reddy

    2012-10-01

    Hollow fibre microfiltration membranes were prepared by solution spinning process using polymer dope containing different amounts of polysulfone (PS), polyvinylpyrollidone (PVP) and ,-dimethylformamide (DMF). Spinning dope having PS: PVP: DMF (w/w) of 15: 5: 80, 15: 7: 78 and 17: 8: 75 were used for spinning to obtain hollow fibres having different dimensions (outer and inner diameters) and pore characteristics. Relatively high water permeability was observed for hollow fibre membrane spun from 15 wt. % solution than 17 wt. % PS solution having the same PVP/PS ratio of 0.47. Decrease of the PVP/PS ratio to 0.33 in the dope solution of 15 wt.%PS solution produced hollow fibre membrane with lower flux. By changing the spinning parameters, fibre with different dimensions were obtained without a significant change in microstructural morphology. The flux decline due to fouling for the permeation of PEO/BSA solution was maximum for the hollow fibre membrane obtained from 15 wt. % PS solution while a steady flux with slight fouling was observed for the hollow fibre membrane obtained from 17 wt. %PS solution, when the PVP/PS ratio was 0.47.

  7. A novel In-situ Enzymatic Cleaning Method for Reducing Membrane Fouling in Membrane Bioreactors (MBRs

    Directory of Open Access Journals (Sweden)

    M. R. Bilad

    2016-05-01

    Full Text Available A novel in-situ enzymatic cleaning method was developed for fouling control in membrane bioreactors (MBRs. It is achieved by bringing the required enzymes near the membrane surface by pulling the enzymes to a magnetic membrane (MM surface by means of magnetic forces, exactly where the cleaning is required. To achieve this, the enzyme was coupled to a magnetic nanoparticle (MNP and the membrane it self was loaded with MNP. The magnetic activity was turned by means of an external permanent magnet. The effectiveness of concept was tested in a submerged membrane filtration using the model enzyme-substrate of Bacillus subitilis xylanase-arabinoxylan. The MM had almost similar properties compared to the unloaded ones, except for its well distributed MNPs. The enzyme was stable during coupling conditions and the presence of coupling could be detected using a high-performance anion-exchange chromatography (HPAEC analysis and Fourier transform infrared spectroscopy (FTIR. The system facilitated an in-situ enzymatic cleaning and could be effectively applied for control fouling in membrane bioreactors (MBRs.

  8. Carbon nanotube fiber microelectrodes show a higher resistance to dopamine fouling.

    Science.gov (United States)

    Harreither, Wolfgang; Trouillon, Raphaël; Poulin, Philippe; Neri, Wilfrid; Ewing, Andrew G; Safina, Gulnara

    2013-08-06

    We have compared the properties and resistance to DA fouling of a carbon nanotube fiber (CNTF) microelectrode to a traditional carbon fiber (CF) microelectrode. These two materials show comparable electrochemical activities for outer-sphere and inner-sphere redox reactions. Although the CNTF might have a higher intrinsic RC constant, thus limiting its high-frequency behavior, the CNTF shows a significantly higher durability than the CF in terms of electrode stability. During constant oxidation of 100 μM DA, the signal measured by the CNTF microelectrode shows a 2-h window over which no decrease in current is observed. Under the same conditions, the current obtained at the CF microelectrode decreases by almost 50%. A model of the fouling process, assuming the formation of growing patches of insulator on the surface, has been compared to the data. This model is found to be in good agreement with our results and indicates a growth rate of the patches in the 0.1-2 nm s(-1) range.

  9. Concentration of field and skim latex by microfiltration - membrane fouling and biochemical methane potential of serum.

    Science.gov (United States)

    Thongmak, Narumol; Sridang, Porntip; Puetpaiboon, Udomphon; Grasmick, Alain

    2015-01-01

    Cross-flow microfiltration was used to concentrate field and skim latex suspensions and recover the smallest compounds (proteins, sugars, etc.) in permeate (serum solutions). The experiments were performed in a lab-scale microfiltration unit equipped with ceramic membranes. In continuous mode, the operations were performed at constant trans-membrane pressure (0.5 bars), constant cross-flow velocity (3 m/s) and constant temperature (28 ± 2°C). In retentate, the volumetric concentration factor was only close to 2 (about 54% of total solid content, TSC) when concentrating the field latex suspensions, and it reached 10 (close to 40% TSC) when concentrating skim latex suspensions. The quality of retentate suspensions let envisage a significant potential of industrial valorization. The membrane fouling rates appeared as an increasing function of dry rubber content suspension, and the main fouling origin (94%) was linked to a reversible accumulation of suspended compounds on the membrane surface. Permeate appeared as a clear yellow solution containing the smallest soluble organic fractions that show a high degree of biodegradability when using biochemical methane potential tests. The chemical oxygen demand (COD) removal was then higher than 92% and the methane production yield was close to 0.29 NLCH4/gCODremoved. The association of a membrane separation step and anaerobic digestion appeared, then, as a relevant solution to recover rubber content from skim latex suspensions and energy from the anaerobic digestion of serum.

  10. Enzymatic treatment for controlling irreversible membrane fouling in cross-flow humic acid-fed ultrafiltration

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Chien-Hwa [Department of Civil and Environment Engineering, Nanya Institute of Technology, Taoyuan, Taiwan (China); Fang, Lung-Chen; Lateef, Shaik Khaja [Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan (China); Wu, Chung-Hsin, E-mail: chunghsinwu@yahoo.com.tw [Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, 415 Chien Kung Road, Kaohsiung 807, Taiwan (China); Lin, Cheng-Fang [Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan (China)

    2010-05-15

    Exploring reasonable ways to remove foulant is of great importance in order to allow sustainable operation of ultrafiltration (UF) membranes in water/wastewater treatment technology. Compounds of organic and inorganic origin largely contribute to irreversible fouling. This study attempted to remove problem of UF membrane fouling by using four different enzymes including {alpha}-amylase, lipase, cellulase and protease. This investigation showed that none of the above mentioned enzymes was found to be effective for the removal of foulant when used alone. However, when these enzymes were used in combination with NaOH and citric acid, about 90% cleaning was achieved. The addition of non-ionic surfactant to the enzymatic solution appears to increase the efficiency of flux recovery by reducing the adhesion of foulant species to the membrane surface through the decrease of contact angle. Field emission gun scanning electron microscopy, Fourier transform infrared spectroscopy and atomic force microscopy (AFM) techniques were employed to qualitatively illustrate the foulant characteristics. The surface roughness through AFM was used to explain the potential mechanism for the enzymatic cleaning.

  11. Sustainable operation of submerged Anammox membrane bioreactor with recycling biogas sparging for alleviating membrane fouling.

    Science.gov (United States)

    Li, Ziyin; Xu, Xindi; Xu, Xiaochen; Yang, FengLin; Zhang, ShuShen

    2015-12-01

    A submerged anaerobic ammonium oxidizing (Anammox) membrane bioreactor with recycling biogas sparging for alleviating membrane fouling has been successfully operated for 100d. Based on the batch tests, a recycling biogas sparging rate at 0.2m(3)h(-1) was fixed as an ultimate value for the sustainable operation. The mixed liquor volatile suspended solid (VSS) of the inoculum for the long operation was around 3000mgL(-1). With recycling biogas sparging rate increasing stepwise from 0 to 0.2m(3)h(-1), the reactor reached an influent total nitrogen (TN) up to 1.7gL(-1), a stable TN removal efficiency of 83% and a maximum specific Anammox activity (SAA) of 0.56kg TNkg(-1) VSSd(-1). With recycling biogas sparging rate at 0.2 m(3) h(-1) (corresponding to an aeration intensity of 118m(3)m(-2)h(-1)), the membrane operation circle could prolong by around 20 times compared to that without gas sparging. Furthermore, mechanism of membrane fouling was proposed. And with recycling biogas sparging, the VSS and EPS content increasing rate in cake layer were far less than the ones without biogas sparging. The TN removal performance and sustainable membrane operation of this system showed the appealing potential of the submerged Anammox MBR with recycling biogas sparging in treating high-strength nitrogen-containing wastewaters.

  12. Finding Balance Between Biological Groundwater Treatment and Treated Injection Water

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Mark A.; Nielsen, Kellin R.; Byrnes, Mark E.; Simmons, Sally A.; Morse, John J.; Geiger, James B.; Watkins, Louis E.; McFee, Phillip M.; Martins, K.

    2015-01-14

    At the U.S. Department of Energy’s Hanford Site, CH2M HILL Plateau Remediation Company operates the 200 West Pump and Treat which was engineered to treat radiological and chemical contaminants in groundwater as a result of the site’s former plutonium production years. Fluidized bed bioreactors (FBRs) are used to remove nitrate, metals, and volatile organic compounds. Increasing nitrate concentrations in the treatment plant effluent and the presence of a slimy biomass (a typical microorganism response to stress) in the FBRs triggered an investigation of nutrient levels in the system. Little, if any, micronutrient feed was coming into the bioreactors. Additionally, carbon substrate (used to promote biological growth) was passing through to the injection wells, causing biological fouling of the wells and reduced specific injectivity. Adjustments to the micronutrient feed improved microorganism health, but the micronutrients were being overfed (particularly manganese) plugging the injection wells further. Injection well rehabilitation to restore specific injectivity required repeated treatments to remove the biological fouling and precipitated metal oxides. A combination of sulfamic and citric acids worked well to dissolve metal oxides and sodium hypochlorite effectively removed the biological growth. Intensive surging and development techniques successfully removed clogging material from the injection wells. Ultimately, the investigation and nutrient adjustments took months to restore proper balance to the microbial system and over a year to stabilize injection well capacities. Carefully tracking and managing the FBRs and well performance monitoring are critical to balancing the needs of the treatment system while reducing fouling mechanisms in the injection wells.

  13. Evaluation of anti-fouling performance for ion-rod water treater with automatic dynamic simulator of fouling%离子棒水处理器的阻垢性能评价

    Institute of Scientific and Technical Information of China (English)

    孙灵芳; 杨善让; 秦裕琨; 徐志明

    2005-01-01

    The application of a novel Automatic Dynamic Simulator of Fouling (ADSF) to evaluate the effectiveness of ion-rod water treater is reported.The effects of some parameters of the water treater were studied with an ADSF made according to patented technology, and orthogonal experimental design was adopted with the use of artificial hard water.Experimental results validated that the ion-rod water treater could mitigate fouling,and the anti-fouling efficiency varies with the test conditions.The anti-fouling efficiency of treater increased with the increase of flow velocity in the range of 0.8-1.2 m·s-1 and output voltage in the range of 7500-15000 V.The efficiency weat up initially, and then went down with the increase in hardness.The rough surface of ion-rod was superior to the smooth one.The order of influence on treater performance with respect to these factors was as follows: water hardness, roughness of surface, flow velocity and output voltage.The research also provided a guide to improving the performance of ion-rod water treater.

  14. Preparation of Calcium Carbonate Nanoparticles with a Continuous Gas-liquid Membrane Contactor:Particles Morphology and Membrane Fouling

    Institute of Scientific and Technical Information of China (English)

    JIA Zhiqian; CHANG Qing; QIN Jin; MAMAT Aynur

    2013-01-01

    Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor.The effects of Ca(OH)2 concentration,CO2 pressure and liquid flow velocity on the particles morphology,pressure drop and membrane fouling were studied.With rising Ca(OH)2 concentrations,the average size of the particles increased.The effects of Ca(OH)2 concentration and CO2 pressure on particles were not apparent under the experimental conditions.When the Ca(OH)2 concentration and liquid flow velocity were high,or the CO2 pressure was low,the fouling on the membrane external surface at the contactor entrance was serious due to liquid leakage,whereas the fouling was slight at exit.The fouling on the membrane inner-surface at entrance was apparent due to adsorption of raw materials.The membrane can be recovered by washing with dilute hydrochloric acid and reused for at least 6 times without performance deterioration.

  15. Effect of free calcium concentration and ionic strength on alginate fouling in cross-flow membrane filtration

    NARCIS (Netherlands)

    Brink, van den P.; Zwijnenburg, A.; Smith, G.; Temmink, B.G.; Loosdrecht, van M.C.

    2009-01-01

    Extracellular polymeric substances (EPS) are generally negatively charged polymers. Membrane fouling in membrane bioreactors (MBRs) by EPS is therefore influenced by the water chemistry of the mixed liquor (calcium concentration, foulant concentration and ionic strength). We used alginate as a model

  16. System for measuring the effect of fouling and corrosion on heat transfer under simulated OTEC conditions. [HTAU and LABTTF codes

    Energy Technology Data Exchange (ETDEWEB)

    Fetkovich, J.G.

    1976-12-01

    A complete system designed to measure, with high precision, changes in heat transfer rates due to fouling and corrosion of simulated heat exchanger tubes, at sea and under OTEC conditions is described. All aspects of the system are described in detail, including theory, mechanical design, electronics design, assembly procedures, test and calibration, operating procedures, laboratory results, field results, and data analysis programs.

  17. Impact of PAC Fines in Fouling of Polymeric and Ceramic Low-Pressure Membranes for Drinking Water Treatment

    Directory of Open Access Journals (Sweden)

    Laurent Oligny

    2016-07-01

    Full Text Available This study assessed the issue of membrane fouling in a Hybrid Membrane Process (HMP due to the export of powdered activated carbon (PAC fines from a pretreatment contactor. Two parallel pilot-scale ceramic and polymeric membranes were studied. Reversible and irreversible foulings were measured following three cleaning procedures: Physical backwashing (BW, chemically enhanced backwashing (CEB and Clean-in-Place (CIP. The impacts on fouling of membrane type, operation flux increase and the presence/absence of the PAC pretreatment were investigated. Membranes without pretreatment were operated in parallel as a control. In addition, CIP washwaters samples were analyzed to measure organic and inorganic foulants removed from the membranes. It was observed that for the polymeric membranes, fouling generally increased with the presence of the PAC pretreatment because of the export of fines. On the contrary, the ceramic membranes were not significantly impacted by their presence. The analysis of CIP washwaters showed a greater total organic carbon (TOC content on membranes with a PAC pretreatment while no similar conclusion could be made for inorganic foulants.

  18. Impact of PAC Fines in Fouling of Polymeric and Ceramic Low-Pressure Membranes for Drinking Water Treatment

    Science.gov (United States)

    Oligny, Laurent; Bérubé, Pierre R.; Barbeau, Benoit

    2016-01-01

    This study assessed the issue of membrane fouling in a Hybrid Membrane Process (HMP) due to the export of powdered activated carbon (PAC) fines from a pretreatment contactor. Two parallel pilot-scale ceramic and polymeric membranes were studied. Reversible and irreversible foulings were measured following three cleaning procedures: Physical backwashing (BW), chemically enhanced backwashing (CEB) and Clean-in-Place (CIP). The impacts on fouling of membrane type, operation flux increase and the presence/absence of the PAC pretreatment were investigated. Membranes without pretreatment were operated in parallel as a control. In addition, CIP washwaters samples were analyzed to measure organic and inorganic foulants removed from the membranes. It was observed that for the polymeric membranes, fouling generally increased with the presence of the PAC pretreatment because of the export of fines. On the contrary, the ceramic membranes were not significantly impacted by their presence. The analysis of CIP washwaters showed a greater total organic carbon (TOC) content on membranes with a PAC pretreatment while no similar conclusion could be made for inorganic foulants. PMID:27399788

  19. Long-term performance and fouling analysis of full-scale direct nanofiltration (NF) installations treating anoxic groundwater

    NARCIS (Netherlands)

    Beyer, F.; Rietman, B.M.; Zwijnenburg, A.; Brink, van den P.; Vrouwenvelder, J.S.; Jarzembowska, M.; Laurinonyte, J.; Stams, A.J.M.; Plugge, C.M.

    2014-01-01

    Long-term performance and fouling behavior of four full-scale nanofiltration (NF) plants, treating anoxic groundwater at 80% recovery for drinking water production, were characterized and compared with oxic NF and reverse osmosis systems. Plant operating times varied between 6 and 10 years and pretr

  20. Triblock Copolymers with Grafted Fluorine-Free Amphiphilic Non-Ionic Side Chains for Antifouling and Fouling-Release Applications

    Energy Technology Data Exchange (ETDEWEB)

    Y Cho; H Sundaram; C Weinman; M Paik; M Dimitriou; J Finlay; M Callow; J Callow; E Kramer; C Ober

    2011-12-31

    Fluorine-free, amphiphilic, nonionic surface active block copolymers (SABCs) were synthesized through chemical modification of a polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene triblock copolymer precursor with selected amphiphilic nonionic Brij and other surfactants. Amphiphilicity was imparted by a hydrophobic aliphatic group combined with a hydrophilic poly(ethylene glycol) (PEG) group-containing moiety. The surfaces were characterized by dynamic water contact angle, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) analysis. In biofouling assays, settlement (attachment) of both spores of the green alga Ulva and cells of the diatom Navicula on SABCs modified with Brij nonionic side chains was significantly reduced relative to a PDMS standard, with a nonionic surfactant combining a PEG group and an aliphatic moiety demonstrating the best performance. Additionally, a fouling-release assay using sporelings (young plants) of Ulva and Navicula suggested that the SABC derived from nonionic Brij side chains also out-performed PDMS as a fouling-release material. Good antifouling and fouling-release properties were not demonstrated for the other two amphiphilic surfaces derived from silicone and aromatic group containing nonionic surfactants included in this study. The results suggest that small differences in chemical surface functionality impart more significant changes with respect to the antifouling settlement and fouling-release performance of materials than overall wettability behavior.

  1. Relationship of fouling diatom number and chlorophyll-a value from Zuari estuary, Goa (west coast of India)

    Digital Repository Service at National Institute of Oceanography (India)

    Redekar, P.D.; Wagh, A

    of cell biomass of fouling diatoms and the chlorophyll -a value observed over a period of 4 days of immersion of glass slide panel in 1 m depth in the estuarine environment in Zuari estuary. Generally. diatom number showed increasing trend from 1st to 4th...

  2. Facile fouling resistant surface modification of microfiltration cellulose acetate membranes by using amino acid L-DOPA.

    Science.gov (United States)

    Azari, Sara; Zou, Linda; Cornelissen, Emile; Mukai, Yasushito

    2013-01-01

    A major obstacle in the widespread application of microfiltration membranes in the wet separation processes such as wastewater treatment is the decline of permeates flux as a result of fouling. This study reports on the surface modification of cellulose acetate (CA) microfiltration membrane with amino acid L-3,4-dihydroxy-phenylalanine (L-DOPA) to improve fouling resistance of the membrane. The membrane surface was characterised using Fourier transform infrared spectroscopy (FTIR), water contact angle and zeta potential measurement. Porosity measurement showed a slight decrease in membrane porosity due to coating. Static adsorption experiments revealed an improved resistance of the modified membranes towards the adhesion of bovine serum albumin (BSA) as the model foulant. Dead end membrane filtration tests exhibited that the fouling resistance of the modified membranes was improved. However, the effect of the modification depended on the foulant solution concentration. It is concluded that L-DOPA modification is a convenient and non-destructive approach to enable low-BSA adhesion surface modification of CA microfiltration membranes. Nevertheless, the extent of fouling resistance improvement depends on the foulant concentration.

  3. Characteristics of meso-particles formed in coagulation process causing irreversible membrane fouling in the coagulation-microfiltration water treatment.

    Science.gov (United States)

    Ding, Q; Yamamura, H; Murata, N; Aoki, N; Yonekawa, H; Hafuka, A; Watanabe, Y

    2016-09-15

    In coagulation-membrane filtration water treatment processes, it is still difficult to determine the optimal coagulation condition to minimize irreversible membrane fouling. In microfiltration (MF), meso-particles (i.e., 20 nm-0.5 μm) are thought to play an important role in irreversible membrane fouling, especially their characteristics of particle number (PN) and zeta potential (ZP). In this study, a new nanoparticle tracker combined a high-output violet laser with a microscope was developed to identify the physicochemical characteristics of these microscopic and widely dispersed meso-particles. The effects of pH and coagulant dose on ZP and PN of micro-particles (i.e., >0.5 μm) and meso-particles were investigated, and then coagulation-MF tests were conducted. As the result, irreversible membrane fouling was best controlled for both types of membranes, while meso-particle ZP approached zero at around pH 5.5 for both types of natural water. Since PN was greatest under these conditions, ZP is more important in determining the extent of irreversible membrane fouling than PN. However, the acidic condition to neutralize meso-particles is not suitable for actual operation, as considering residual aluminum concentration, pipe corrosion, and chlorination efficiency. It is therefore necessary to investigate coagulants or other methods for the appropriate modification of meso-particle characteristics.

  4. Enzyme immobilization by fouling in ultrafiltration membranes: Impact of membrane configuration and type on flux behavior and biocatalytic conversion efficacy

    DEFF Research Database (Denmark)

    Luo, Jianquan; Meyer, Anne S.; Jonsson, Gunnar Eigil

    2014-01-01

    and PLGC regenerated cellulose membranes. With these two highly hydrophilic membranes, the ADH enzyme activity was fully retained even after 24h of storage of the membrane. Filtration blocking and resistance models were used to analyze the fouling/immobilization mechanisms and give explanations...

  5. Experimental Study of Membrane Fouling during Crossflow Microfiltration of Yeast and Bacteria Suspensions: Towards an Analysis at the Microscopic Level.

    Science.gov (United States)

    Hassan, Ines Ben; Ennouri, Monia; Lafforgue, Christine; Schmitz, Philippe; Ayadi, Abdelmoneim

    2013-05-10

    Microfiltration of model cell suspensions combining macroscopic and microscopic approaches was studied in order to better understand microbial membrane fouling mechanisms. The respective impact of Saccharomyces cerevisiae yeast and Escherichia coli bacteria on crossflow microfiltration performances was investigated using a multichannel ceramic 0.2 µm membrane. Pure yeast suspensions (5 µm ovoid cells) and mixtures of yeast and bacteria (1 to 2.5 µm rod shape cells) were considered in order to analyse the effect of interaction between these two microorganisms on fouling reversibility. The resistances varied significantly with the concentration and characteristics of the microorganisms. Membrane fouling with pure yeast suspension was mainly reversible. For yeast and bacteria mixed suspensions (6 g L-1 yeast concentration) the increase in bacteria from 0.15 to 0.30 g L-1 increased the percentage of normalized reversible resistance. At 10 g L-1 yeast concentration, the addition of bacteria tends to increase the percentage of normalized irreversible resistance. For the objective of performing local analysis of fouling, an original filtration chamber allowing direct in situ observation of the cake by confocal laser scanning microscopy (CLSM) was designed, developed and validated. This device will be used in future studies to characterize cake structure at the microscopic scale.

  6. Experimental Study of Membrane Fouling during Crossflow Microfiltration of Yeast and Bacteria Suspensions: Towards an Analysis at the Microscopic Level

    Directory of Open Access Journals (Sweden)

    Abdelmoneim Ayadi

    2013-05-01

    Full Text Available Microfiltration of model cell suspensions combining macroscopic and microscopic approaches was studied in order to better understand microbial membrane fouling mechanisms. The respective impact of Saccharomyces cerevisiae yeast and Escherichia coli bacteria on crossflow microfiltration performances was investigated using a multichannel ceramic 0.2 µm membrane. Pure yeast suspensions (5 µm ovoid cells and mixtures of yeast and bacteria (1 to 2.5 µm rod shape cells were considered in order to analyse the effect of interaction between these two microorganisms on fouling reversibility. The resistances varied significantly with the concentration and characteristics of the microorganisms. Membrane fouling with pure yeast suspension was mainly reversible. For yeast and bacteria mixed suspensions (6 g L−1 yeast concentration the increase in bacteria from 0.15 to 0.30 g L−1 increased the percentage of normalized reversible resistance. At 10 g L−1 yeast concentration, the addition of bacteria tends to increase the percentage of normalized irreversible resistance. For the objective of performing local analysis of fouling, an original filtration chamber allowing direct in situ observation of the cake by confocal laser scanning microscopy (CLSM was designed, developed and validated. This device will be used in future studies to characterize cake structure at the microscopic scale.

  7. Transparent exopolymer particles (TEP) removal efficiency by a combination of coagulation and ultrafiltration to minimize SWRO membrane fouling

    KAUST Repository

    Li, Sheng

    2016-07-02

    This study investigated the impact of coagulation on the transformation between colloidal and particulate transparent exopolymer particles (TEP) in seawater; and the effectiveness of a combined pretreatment consisting of coagulation and UF on minimizing TEP fouling of seawater reverse osmosis (SWRO) membranes. Coagulation with ferric chloride at pH 5 substantially transformed colloidal TEP (0.1–0.4) into particulate TEP (>0.4) leading to a better membrane fouling control. Both 50 and 100 kDa molecular weight cut-off (MWCO) UF membranes removed most of particulate and colloidal TEP without the assistance of coagulation, but coagulation is still necessary for better UF fouling control. The improvement of combined SWRO pretreatment with coagulation and 50 kDa UF membranes was not that much significant compared to UF pretreatment with 50 KDa alone. Therefore, the minimal coagulant dosage for seawater containing TEP should be based on the UF fouling control requirements rather than removal efficiency. © 2016 Elsevier Ltd

  8. Bioactive coating with low-fouling polymers for the development of biocompatible vascular implants

    Science.gov (United States)

    Thalla, Pradeep Kumar

    The replacement of occluded blood vessels and endovascular aneurysm repair (EVAR) are performed with the use of synthetic vascular grafts and stent grafts, respectively. Both implants lead to frequent clinical complications that are different but due to a similar problem, namely the inadequate surface properties of the polymeric biomaterials used (generally polyethylene terephthalate (PET) or expanded polytetrafluoroethylene (ePTFE)). Therefore the general objective of this thesis was to create a versatile bioactive coating on vascular biomaterials that reduce material-induced thrombosis and promote desired cell interactions favorable to tissue healing around implants. The use of low-fouling backgrounds was decided in order to reduce platelet adhesion as well as the non-specific protein adsorption and thus increase the bioactivity of immobilized biomolecules. As part of the preliminary objective, a multi-arm polyethylene glycol (PEG) was chosen to create a versatile low-fouling surface, since the current coating methods are far from being versatile and rely on the availability of compatible functional groups on both PEG and the host surface. This PEG coating method was developed by taking advantage of novel primary amine-rich plasma polymerized coatings (LP). As demonstrated by quartz crystal microbalance with dissipation (QCM-D), fluorescence measurements and platelet adhesion assays, our PEG coatings exhibited low protein adsorption and almost no platelet adhesion after 15 min perfusion in whole blood. Although protein adsorption was not completely abrogated and short-term platelet adhesion assay was clearly insufficient to draw conclusions for long-term prevention of thrombosis in vivo, the low-fouling properties of this PEG coating were sufficient to be exploited for further coupling of bioactive molecules to create bioactive coatings. Therefore, as a part of the second objective, an innovative and versatile bioactive coating was developed on PEG and

  9. Design of poly(vinylidene fluoride)-g-p(hydroxyethyl methacrylate-co-N-isopropylacrylamide) membrane via surface modification for enhanced fouling resistance and release property

    Science.gov (United States)

    Zhao, Guili; Chen, Wei Ning

    2017-03-01

    Thermo-sensitive polymer poly(N-isopropylacrylamide) (PNIPAAm), hydrophilic polymer poly(hydroxyethyl methacrylate) (PHEMA) and copolymer p(hydroxyethyl methacrylate-co-N-isopropylacrylamide) [P(HEMA-co-NIPAAm)] were synthesized onto poly(vinylidene fluoride) (PVDF) membrane via atom transfer radical polymerization (ATRP) in order to improve not only fouling resistance but also fouling release property. The physicochemical properties of membranes including hydrophilicity, morphology and roughness were examined by contact angle analyzer, scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. The antifouling property of membranes was improved remarkably after surface modification according to protein and bacterial adhesion testing, and filtration experiment. Minimum protein adsorption and bacterial adhesion were both obtained on PVDF-g-P(HEMA-co-NIPAAm) membrane, with reduction by 44% and 71% respectively compared to the pristine membrane. The minimum bacterial cells after detachment at 25 °C were observed on the PVDF-g-P(HEMA-co-NIPAAm) membrane with the detachment rate of 77%, indicating high fouling release property. The filtration testing indicated that the copolymer modified membrane exhibited high resistance to protein fouling and the foulant on the surface was released and removed easily by washing, suggesting high fouling release and easy-cleaning capacity. This study provides useful insight in the combined "fouling resistance" and "fouling release" property of P(HEMA-co-NIPAAm) for PVDF membrane modification, even for other types of the membrane in wide application.

  10. All biology is computational biology

    Science.gov (United States)

    2017-01-01

    Here, I argue that computational thinking and techniques are so central to the quest of understanding life that today all biology is computational biology. Computational biology brings order into our understanding of life, it makes biological concepts rigorous and testable, and it provides a reference map that holds together individual insights. The next modern synthesis in biology will be driven by mathematical, statistical, and computational methods being absorbed into mainstream biological training, turning biology into a quantitative science. PMID:28278152

  11. Effects of dissolved organic matters (DOMs) on membrane fouling in anaerobic ceramic membrane bioreactors (AnCMBRs) treating domestic wastewater.

    Science.gov (United States)

    Yue, Xiaodi; Koh, Yoong Keat Kelvin; Ng, How Yong

    2015-12-01

    Anaerobic membrane bioreactors (AnMBRs) have been regarded as a potential solution to achieve energy neutrality in the future wastewater treatment plants. Coupling ceramic membranes into AnMBRs offers great potential as ceramic membranes are resistant to corrosive chemicals such as cleaning reagents and harsh environmental conditions such as high temperature. In this study, ceramic membranes with pore sizes of 80, 200 and 300 nm were individually mounted in three anaerobic ceramic membrane bioreactors (AnCMBRs) treating real domestic wastewater to examine the treatment efficiencies and to elucidate the effects of dissolved organic matters (DOMs) on fouling behaviours. The average overall chemical oxygen demands (COD) removal efficiencies could reach around 86-88%. Although CH4 productions were around 0.3 L/g CODutilised, about 67% of CH4 generated was dissolved in the liquid phase and lost in the permeate. When filtering mixed liquor of similar properties, smaller pore-sized membranes fouled slower in long-term operations due to lower occurrence of pore blockages. However, total organic removal efficiencies could not explain the fouling behaviours. Liquid chromatography-organic carbon detection, fluorescence spectrophotometer and high performance liquid chromatography coupled with fluorescence and ultra-violet detectors were used to analyse the DOMs in detail. The major foulants were identified to be biopolymers that were produced in microbial activities. One of the main components of biopolymers--proteins--led to different fouling behaviours. It is postulated that the proteins could pass through porous cake layers to create pore blockages in membranes. Hence, concentrations of the DOMs in the soluble fraction of mixed liquor (SML) could not predict membrane fouling because different components in the DOMs might have different interactions with membranes.

  12. Impact of algal organic matter released from Microcystis aeruginosa and Chlorella sp. on the fouling of a ceramic microfiltration membrane.

    Science.gov (United States)

    Zhang, Xiaolei; Devanadera, Ma Catriona E; Roddick, Felicity A; Fan, Linhua; Dalida, Maria Lourdes P

    2016-10-15

    Algal blooms lead to the secretion of algal organic matter (AOM) from different algal species into water treatment systems, and there is very limited information regarding the impact of AOM from different species on the fouling of ceramic microfiltration (MF) membranes. The impact of soluble AOM released from Microcystis aeruginosa and Chlorella sp. separately and together in feedwater on the fouling of a tubular ceramic microfiltration membrane (alumina, 0.1 μm) was studied at lab scale. Multi-cycle MF tests operated in constant pressure mode showed that the AOM (3 mg DOC L(-1)) extracted from the cultures of the two algae in early log phase of growth (12 days) resulted in less flux decline compared with the AOM from stationary phase (35 days), due to the latter containing significantly greater amounts of high fouling potential components (protein and humic-like substances). The AOM released from Chlorella sp. at stationary phase led to considerably greater flux decline and irreversible fouling resistance compared with that from M. aeruginosa. The mixture of the AOM (1:1, 3 mg DOC L(-1)) from the two algal species showed more similar flux decline and irreversible fouling resistance to the AOM from M. aeruginosa than Chlorella sp. This was due to the characteristics of the AOM mixture being more similar to those for M. aeruginosa than Chlorella sp. The extent of the flux decline for the AOM mixture after conventional coagulation with aluminium chlorohydrate or alum was reduced by 70%.

  13. Flux, rejection and fouling during microfiltration and ultrafiltration of sugar palm sap using a pilot plant scale

    Directory of Open Access Journals (Sweden)

    Wanichapichart, P.

    2006-07-01

    Full Text Available The possibility of using a pilot plant scale microfiltration (MF and ultrafiltration (UF to clarify and reduce number of bacteria, yeast and mould of sugar palm sap was studied. The membrane used was multi channel tubular ceramic membrane (ZrO2-TiO2 with membrane pore size 0.2 and 0.1 μm and molecular weight cut off (MWCO 300 and 50 kDa for microfiltration and ultrafiltration respectively. The experiment was carried out to investigate the rejection of the components in sugar palm sap, permeate flux and fouling characteristics. The results showed that the turbidity, the total solid, the viscosity and the numbers of bacteria, yeast and mould in the permeate obtained by MF and UF were reduced significantly compared to those of fresh sugar palm sap. The total soluble solid, total sugar, reducing sugar and pH were not affected by MF and UF. The permeate fluxes for all membranes were reduced greatly as the volume concentration ratio (VCR increased due to severe fouling. The irreversible fouling on membrane surface and/or inside the membrane tended to increase with increasing membrane pore size or MWCO. The result also suggested that protein and small particle in the sugar palm sap were probably responsible for the internal fouling of large pore size membrane. According to the physical, chemical and microorganism quality results, both MF and UF showed the potential use for improving the quality of sugar palm sap but flux reduction due to fouling was a major problem affecting the process performance.

  14. Simulation of the performance of heat exchanger networks under fouling condition; Simulacao do desempenho de redes de trocadores de calor sujeitas a incrustacao

    Energy Technology Data Exchange (ETDEWEB)

    Negrao, Cezar O.R.; Madi, Marcio; Massoqueti, Rodrigo [Centro Federal de Educacao Tecnologica do Parana (CEFET-PR), Curitiba, PR (Brazil)

    2004-07-01

    Heat exchanger fouling has received great attention in recent years in the oil refining industry, once this problem has caused significant losses in energy recovery. The current work presents a simulation model to predict the thermal performance of a fouled heat exchanger network. Steady-state heat balance equations are employed to evaluate the outlet temperatures of the heat exchangers. The flow is considered single-phased within the heat exchanger and the fouling thermal resistance is admitted to evolve linearly along the time. The results are compared to measured values, showing they agree quite well. Besides, the approach can be applied to identify the adequate cleaning time of the heat exchangers. (author)

  15. Enabling fiber optic serotyping of pathogenic bacteria through improved anti-fouling functional surfaces

    Science.gov (United States)

    Janssen, K. P. F.; Knez, K.; Vanysacker, L.; Schrooten, J.; Spasic, D.; Lammertyn, J.

    2012-06-01

    Significant research efforts are continually being directed towards the development of sensitive and accurate surface plasmon resonance biosensors for sequence specific DNA detection. These sensors hold great potential for applications in healthcare and diagnostics. However, the performance of these sensors in practical usage scenarios is often limited due to interference from the sample matrix. This work shows how the co-immobilization of glycol (PEG) diluents or ‘back filling’ of the DNA sensing layer can successfully address these problems. A novel SPR based melting assay is used for the analysis of a synthetic oligomer target as well as PCR amplified genomic DNA extracted from Legionella pneumophila. The benefits of sensing layer back filling on the assay performance are first demonstrated through melting analysis of the oligomer target and it is shown how back filling enables accurate discrimination of Legionella pneumophila serogroups directly from the PCR reaction product with complete suppression of sensor fouling.

  16. Engineering Hydrophobic Organosilica Nanoparticle-Doped Nanofibers for Enhanced and Fouling Resistant Membrane Distillation

    KAUST Repository

    Hammami, Mohammed Amen

    2016-12-15

    Engineering and scaling-up new materials for better water desalination are imperative to find alternative fresh water sources to meet future demands. Herein, the fabrication of hydrophobic poly(ether imide) composite nanofiber membranes doped with novel ethylene-pentafluorophenylene-based periodic mesoporous organosilica nanoparticles is reported for enhanced and fouling resistant membrane distillation. Novel organosilica nanoparticles were homogeneously incorporated into electrospun nanofiber membranes depicting a proportional increase of hydrophobicity to the particle contents. Direct contact membrane distillation experiments on the organosilica-doped membrane with only 5% doping showed an increase of flux of 140% compared to commercial membranes. The high porosity of organosilica nanoparticles was further utilized to load the eugenol antimicrobial agent which produced a dramatic enhancement of the antibiofouling properties of the membrane of 70% after 24 h.

  17. Nanostructure on taro leaves resists fouling by colloids and bacteria under submerged conditions.

    Science.gov (United States)

    Ma, Jianwei; Sun, Yuekai; Gleichauf, Karla; Lou, Jun; Li, Qilin

    2011-08-16

    The antifouling and self-cleaning properties of plants such as Nelumbo nucifera (lotus) and Colocasia esculenta (taro) have been attributed to the superhydrophobicity resulting from the hierarchical surface structure of the leaf and the air trapped between the nanosized epicuticular wax crystals. The reported study showed that the nanostructures on the taro leaf surfaces were also highly resistant to particle and bacterial adhesion under completely wetted conditions. Adhesion force measurements using atomic force microscopy revealed that the adhesion force on top of the papilla as well as the area around it was markedly lower than that on the edge of an epidermal cell. The decreased adhesion force and the resistance to particle and bacterial adhesion were attributed to the dense nanostructures found on the epidermal papilla and the area surrounding it. These results suggest that engineered surfaces with properly designed nanoscale topographic structures could potentially reduce or prevent particle/bacterial fouling under submerged conditions.

  18. EQUIVALENCY OF FOULING THICKNESS WITH DENATURED Β-LG IN HEATING OF MILK

    Directory of Open Access Journals (Sweden)

    Heriberto Molina-Pérez

    2015-03-01

    Full Text Available This work presents an approach to match the foaling thickness of dairy food and the concentration of denatured β-lg (β-lactoglobuline by a mathematical model. This includes, on the one hand, the dynamic simulation of fouling and, on the other hand, the generation of denatured β-lg under a kinetic model. In both cases a transient energy balance is developed, including the rigorous calculation of the global coefficient, and the properties by the Choi-Okos model. The solution was obtained by a fourth order Runge-Kutta written in Excel’s Macro language Visual Basic. The equivalence concluded with a model obtained by a non-linear multiple regression that relates the concentration of denatured β-lg and the foaling thickness. This methodology is applicable to analysis equipment cleaning in which kinetic cleaning has equality by reduction of the foaling thickness.

  19. Synthesis of polyaluminum chloride with a membrane reactor: Process characteristics and membrane fouling

    Institute of Scientific and Technical Information of China (English)

    Zhiqian Jia; Fei He; Zhongzhou Liu

    2011-01-01

    Polyaluminum chloride was synthesized with a membrane reactor,in which NaOH was added into AlCl3 solution through the membrane's micropores to reduce the NaOH droplets size.The content of the most efficient species increased to about 80%.The process characteristics in the reaction (i.e.,flow velocity,pressure drop),and membrane fouling and cleaning were investigated.The evolution of both flow velocity and pressure drop during the reaction were related to changes in species distribution and solution viscosity.The process characteristics were well interpreted in terms of the Bernoulli equation.After reaction,the membranes were recovered by cleaning with diluted hydrochloride acid.This study is crucial for process design and scale-up of membrane reactors.

  20. Use of Fillers, Pigments and Additives in Fouling-Release Coatings: a Literature Review

    DEFF Research Database (Denmark)

    Tamaev, Nail; Kiil, Søren; Noguer, Albert Camós

    elastomers. As an additional option, pretreatment operations for silica can be considered as they ensure necessary hydrophilic/phobic properties alongside with easy dispersion in the PDMS matrix and lower moisture content. However, in this case, impaired reinforcement is observed [2]. One of the challenges......]. This result is obtained without dependence on type of the filler [3]. It also should be mentioned, that several recent researches opened promising perspectives of embedding of natural sepiolite nanofibers (Mg4Si6O15(OH)2·6H2O), single- or multi-walled carbon nanotubes (CWNTs and MWCNTs), modified graphite...... research must be done in the area of silica action alongside with the nano-structured compounds as a future replacement of traditional fillers. Likewise, the negative impact of a high filler loading on the fouling-release performance, must be thoroughly examined....

  1. Experimental investigation of the behaviour and fate of block copolymers in fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, Stefan Møller

    in the worsening of the fouling-inhibition properties of these complex systems, specially focusing on the behaviour and fate of the block copolymers used as additives. The development of various methods to visualize and quantify processes involving these copolymers are presented. Chapter 1 provides an overview......-release coatings. A coating based on a PDMS binder has been employed as model system in the thesis. The effect of the addition of various PEG-based surfactants and copolymers (i.e. amphiphiles) was investigated by a novel method developed in this project, and the diffusion coefficient and biofouling...... coatings. Images obtained by confocal microscopy proved that the copolymer molecules assemble in spherical domains inside the PDMS coating. The domains are smaller close to the surface and larger in the bulk of the film (with domains as large as 7 µm in diameter). The diffusion of copolymer from the bulk...

  2. Transport phenomena and fouling in vacuum enhanced direct contact membrane distillation: Experimental and modelling

    KAUST Repository

    Naidu, Gayathri

    2016-08-27

    The application of vacuum to direct contact membrane distillation (vacuum enhanced direct contact membrane distillation, V-DCMD) removed condensable gasses and reduced partial pressure in the membrane pores, achieving 37.6% higher flux than DCMD at the same feed temperature. Transfer mechanism and temperature distribution profile in V-DCMD were studied. The empirical flux decline (EFD) model represented fouling profiles of V-DCMD. In a continuous V-DCMD operation with moderate temperature (55 degrees C) and permeate pressure (300 mbar) for treating wastewater ROC, a flux of 16.0 +/- 0.3 L/m(2) h and high quality distillate were achieved with water flushing, showing the suitability of V-DCMD for ROC treatment. (C) 2016 Elsevier B.V. All rights reserved.

  3. Influence of feed composition and membrane fouling on forward osmosis performance

    DEFF Research Database (Denmark)

    Schneider, Carina; Sathyadev Rajmohan, Rajath; Zarebska, Agata

    2016-01-01

    . These membranes were reported to achieve remarkable results in terms of water flux and solute rejection, though little is known whether they are suitable for wastewater treatment. The objective of this study is to investigate 1) which types of wastewater can be treated by FO using biomimetic Aquaporin membranes......Clean water is a basic human need. However, rapid population growth and climate change result in an increase of water demand, whereas the resources of potable water are shrinking. One of the solutions could be to use membrane technology to reclaim clean and safe drinking water from wastewater....... Nonetheless, the existing membrane technologies often face fouling problem that lowers the economic viability of the membrane application in industrial scale. Recent development in the membrane technology indicates that forward osmosis (FO) has a high potential for wastewater treatment, producing high quality...

  4. In situ characterization of fouling in reverse osmosis membranes using electrical impedance spectroscopy

    Science.gov (United States)

    Chilcott, Terry; Antony, Alice; Coster, Hans; Leslie, Greg

    2013-04-01

    Analytical solutions of the Nernst-Planck, Poisson and continuity equations for a membrane undergoing reverse osmosis in a cross-flow system reveal that the flow of alternating ionic charge induced in the membrane during impedance measurements is actively assisted by the flow of water. The actively driven current manifested "inductive" responses in impedance measurements of a Filmtec BW30 reverse osmosis membrane mounted in an Inphaze flat-bed cross-flow module after 16 hours of filtering a mineral salt solution seeded with CaCl2 and NaHCO3 at pressure of 900 kPa. Fitted transfer functions resolved conduction and capacitive properties of four membrane layers, diffusion/concentration phenomenon and a pseudo "inductor" shunted by a conductor. A 10-fold decrease in the shunt conductance correlated with smaller increases in the conductance values for the filtrate and membranous layers, and the onset of fouling diagnosed by a rapid increase in flux decline.

  5. Modelling the link amongst fine-pore diffuser fouling, oxygen transfer efficiency, and aeration energy intensity.

    Science.gov (United States)

    Garrido-Baserba, Manel; Sobhani, Reza; Asvapathanagul, Pitiporn; McCarthy, Graham W; Olson, Betty H; Odize, Victory; Al-Omari, Ahmed; Murthy, Sudhir; Nifong, Andrea; Godwin, Johnnie; Bott, Charles B; Stenstrom, Michael K; Shaw, Andrew R; Rosso, Diego

    2017-03-15

    This research systematically studied the behavior of aeration diffuser efficiency over time, and its relation to the energy usage per diffuser. Twelve diffusers were selected for a one year fouling study. Comprehensive aeration efficiency projections were carried out in two WRRFs with different influent rates, and the influence of operating conditions on aeration diffusers' performance was demonstrated. This study showed that the initial energy use, during the first year of operation, of those aeration diffusers located in high rate systems (with solids retention time - SRT-less than 2 days) increased more than 20% in comparison to the conventional systems (2 > SRT). Diffusers operating for three years in conventional systems presented the same fouling characteristics as those deployed in high rate processes for less than 15 months. A new procedure was developed to accurately project energy consumption on aeration diffusers; including the impacts of operation conditions, such SRT and organic loading rate, on specific aeration diffusers materials (i.e. silicone, polyurethane, EPDM, ceramic). Furthermore, it considers the microbial colonization dynamics, which successfully correlated with the increase of energy consumption (r(2):0.82 ± 7). The presented energy model projected the energy costs and the potential savings for the diffusers after three years in operation in different operating conditions. Whereas the most efficient diffusers provided potential costs spanning from 4900 USD/Month for a small plant (20 MGD, or 74,500 m(3)/d) up to 24,500 USD/Month for a large plant (100 MGD, or 375,000 m(3)/d), other diffusers presenting less efficiency provided spans from 18,000USD/Month for a small plant to 90,000 USD/Month for large plants. The aim of this methodology is to help utilities gain more insight into process mechanisms and design better energy efficiency strategies at existing facilities to reduce energy consumption.

  6. Oil shale fueled FBC power plant - ash deposits and fouling problems

    Energy Technology Data Exchange (ETDEWEB)

    O. Yoffe; A. Wohlfarth; Y. Nathan; S. Cohen; T. Minster [Geological Survey of Israel, Jerusalem (Israel)

    2007-12-15

    41 MWth oil shale fired demonstration power plant was built in 1989 by PAMA in Mishor Rotem, Negev, Israel. The raw material for the plant is the local 'oil shale', which is in fact organic-rich marl. Since then, and until today, the unit is operated at high reliability and availability. At first, heavy soft fouling occurred due to the Circulating Fluidized Bed Combustion (CFBC) mode of operation, which caused a considerable reduction in the heat transfer coefficient of the heat exchangers. By going over to the Fluidized Bed Combustion (FBC) mode of operation the soft fouling phenomenon stopped at once, the heat transfer coefficient improved, and the power plant could be operated at its designed values. After five months of operation at the FBC mode the boiler had to be shut down because Hard Deposits (HD) blocked physically the passes in the boiler. These deposits could be removed only with the help of mechanical devices. During the first two years the boiler had to be stopped, at least, three times a year for deposit cleaning purposes. Research conducted at the plant and in the laboratories of the Geological Survey of Israel enabled us to understand the mechanism of formation of these deposits. The results showed that the HD are formed in two stages: (1) Deposition of very fine ash particles on the pipes of the boiler, as a result of the impact of larger particles on the pipes. The fine particles adhere to the pipes and to each other, and step by step build the deposit. The growth of the deposit on the pipe surface is always perpendicular to the particles flow direction. (2) The deposits harden due to chemical reactions. 17 refs., 14 figs., 5 tabs.

  7. Hybrid SBR–FO system for wastewater treatment and reuse: Operation, fouling and cleaning

    KAUST Repository

    Valladares Linares, Rodrigo

    2016-04-05

    Forward osmosis (FO) is a novel membrane separation process that potentially can be used as an energy-saving alternative to conventional membrane processes. A hybrid sequential batch reactor (SBR)–FO process was explored. In this system, a plate and frame FO cell including two flat-sheet FO membranes was submerged in a bioreactor treating synthetic domestic wastewater. The dissolved organic carbon (DOC) removal efficiency of the system was 98.55%. Total nitrogen removal was 62.4%, with nitrate, nitrite and ammonium removals of 58.4%, 96.2% and 88.4%, respectively. Phosphate removal was almost 100%. The 15-hour cycle average water flux of a virgin membrane with air scouring was 2.95 L/m2·h− 1. Air scouring can help to remove loose foulants from the membrane active layer, thus helping to recover up to 89.5% of the original flux. Chemical cleaning of the fouled active layer of the FO membrane was not as effective as air scouring. Natural organic matter (NOM) characterization methods (liquid chromatography–organic carbon detection (LC–OCD) and 3-D fluorescence excitation emission matrix (FEEM)) show that the FO membrane has a very good performance in rejecting biopolymers, humics and building blocks, but a limited ability in rejecting low molecular weight neutrals. Transparent exopolymer particles (TEP) and other biopolymers might be associated with fouling of the membrane on the support layer. A 1% sodium hypochlorite (NaOCl) cleaning solution was proved to be effective for removing the foulants from the support layer and recovering the original flux.

  8. Fouling of nanofiltration membrane by effluent organic matter: characterization using different organic fractions in wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liqing; WANG Lei; ZHANG Gang; WANG Xudong

    2009-01-01

    The UF membrane with molecular weight cutoff (MWCO) ranging from 2 kDa to 100 kDa and XAD-8 resin were employed to identify the characteristic of molecular weight (MW) distribution of wastewater effluent organic matter (EfOM) in terms of TOC and UV254, as well as the amounts of the hydrophilic/hydrophobic organic fractions in different MW ranges. Then, the nanofiltration (NF) membrane fouling experiments were carried out using the above fractionated water to investigate the effect of MW distribution and hydrophilic/hydrophobic characteristics of EfOM on the membrane flux decline using the fractionated water samples above. The experimental results have shown that 45.61% of the total organics belongs to the low MW one, among which the percentage of the hydrophilic organics with low MW (less than 2 kDa) was up to 28.07%, while that of the hydrophobic organics was 17.54%. In particular, the hydrophilic fraction was found to be the most abundant fraction in the effluents. MW distribution has a significant effect on the membrane fouling. When the MW was less than 30 kDa, the lower the MW, the larger was the specific flux decline, while in the case of MW higher than 30 kDa, the higher the MW, the larger was the specific flux decline, and the decline degree of low MW organics was larger than the high MW one. With the same MW distribution range, specific flux decline of the hydrophilic organic was considerably slower than that of the hydrophobic organic, which indicated that the hydrophobic organic fractions dominantly contribute to the flux decline.

  9. Combinatorial materials research applied to the development of new surface coatings XV: an investigation of polysiloxane anti-fouling/fouling-release coatings containing tethered quaternary ammonium salt groups.

    Science.gov (United States)

    Majumdar, Partha; Crowley, Elizabeth; Htet, Maung; Stafslien, Shane J; Daniels, Justin; VanderWal, Lyndsi; Chisholm, Bret J

    2011-05-09

    As part of ongoing efforts aimed at the development of extensive structure−property relationships for moisture-curable polysiloxane coatings containing tethered quaternary ammonium salt (QAS) moieties for potential application as environmental friendly coatings to combat marine biofouling, a combinatorial/high-throughput (C/HT) study was conducted that was focused on four different compositional variables. The coatings that were investigated were derived from solution blends of a silanol-terminated polydimethylsiloxane (HO-PDMS-OH), QAS-functional alkoxysilane, and methyltriacetoxysilane. The compositional variables investigated were alkoxysilane functionality of the QAS-functional silane, chain length of the monovalent alkyl group attached to the QAS nitrogen atom, concentration of the QAS-functional alkoxysilane, and molecular weight of the HO-PDMS-OH. Of these variables, the composition of the alkoxysilane functionality of the QAS-functional silane was a unique variable that had not been previously investigated. The antifouling (AF) and fouling-release (FR) characteristics of the 24 unique coating compositions were characterized using HT assays based on three different marine microorganisms, namely, the two bacteria, Cellulophaga lytica and Halomonas pacifica, and the diatom, Navicula incerta. Coatings surfaces were characterized by surface energy, water contact angle hysteresis, and atomic force microscopy (AFM). A wide variety of responses were obtained over the compositional space investigated. ANOVA analysis showed that the compositional variables and their interactions significantly influenced AF/FR behaviors toward individual marine microorganisms. It was also found that utilization of the ethoxysilane-functional QASs provided enhanced AF character compared to coatings based on methoxysilane-functional analogues. This was attributed to enhanced surface segregation of QAS groups at the coating-air interface and confirmed by phase images using AFM.

  10. Reduced-Order Dynamic Modeling, Fouling Detection, and Optimal Control of Solar-Powered Direct Contact Membrane Distillation

    KAUST Repository

    Karam, Ayman M.

    2016-12-01

    Membrane Distillation (MD) is an emerging sustainable desalination technique. While MD has many advantages and can be powered by solar thermal energy, its main drawback is the low water production rate. However, the MD process has not been fully optimized in terms of its manipulated and controlled variables. This is largely due to the lack of adequate dynamic models to study and simulate the process. In addition, MD is prone to membrane fouling, which is a fault that degrades the performance of the MD process. This work has three contributions to address these challenges. First, we derive a mathematical model of Direct Contact Membrane Distillation (DCMD), which is the building block for the next parts. Then, the proposed model is extended to account for membrane fouling and an observer-based fouling detection method is developed. Finally, various control strategies are implemented to optimize the performance of the DCMD solar-powered process. In part one, a reduced-order dynamic model of DCMD is developed based on lumped capacitance method and electrical analogy to thermal systems. The result is an electrical equivalent thermal network to the DCMD process, which is modeled by a system of nonlinear differential algebraic equations (DAEs). This model predicts the water-vapor flux and the temperature distribution along the module length. Experimental data is collected to validate the steady-state and dynamic responses of the proposed model, with great agreement demonstrated in both. The second part proposes an extension of the model to account for membrane fouling. An adaptive observer for DAE systems is developed and convergence proof is presented. A method for membrane fouling detection is then proposed based on adaptive observers. Simulation results demonstrate the performance of the membrane fouling detection method. Finally, an optimization problem is formulated to maximize the process efficiency of a solar-powered DCMD. The adapted method is known as Extremum

  11. Aluminum-induced changes in properties and fouling propensity of DOM solutions revealed by UV-vis absorbance spectral parameters.

    Science.gov (United States)

    Zhou, Minghao; Meng, Fangang

    2016-04-15

    The integration of pre-coagulation with ultrafiltration (UF) is expected to not only reduce membrane fouling but also improve natural organic matter (NOM) removal. However, it is difficult to determine the proper coagulant dosage for different water qualities. The objective of this study was to probe the potential of UV-vis spectroscopic analysis to reveal the coagulant-induced changes in the fouling potentials of dissolved organic matter (DOM) and to determine the optimal coagulant dosage. The Zeta potentials (ZPs) and average particle size of the four DOM solutions (Aldrich humic acid (AHA), AHA-sodium alginate (SA), AHA-bovine serum albumin (BSA) and AHA-dextran (DEX)) coagulated with aluminum chloride (AlCl3) were measured. Results showed that increasing the aluminum coagulant dosage induced the aggregation of DOM. Meanwhile, the addition of aluminum coagulant resulted in an increase in DSlope(325-375) (the slope of the log-transformed absorbance spectra from 325 to 375 nm) and a decrease in S(275-295) (the slope of the log-transformed absorption coefficient from 275 to 295 nm) and SR (the ratio of Slope(275-295) and Slope(350-400)). The variations of these spectral parameters (i.e., DSlope(325-375), S(275-295) and SR) correlated well with the aluminum-caused changes in ZPs and average particle size. This implies that spectral parameters have the potential to indicate DOM aggregation. In addition, good correlations of spectral parameters and membrane fouling behaviors (i.e., unified membrane fouling index (UMFI)) suggest that the changes in DSlope(325-375), S(275-295) and SR were indicative of the aluminum-caused alterations of fouling potentials of all DOM solutions. Interestingly, the optimal dosage of aluminum (40 μM for AHA, AHA-BSA, and AHA-DEX) was obtained based on the relation between spectral parameters and fouling behaviors. Overall, the spectroscopic analysis, particularly for the utilization of spectral parameters, provided a convenient approach

  12. Forward Osmosis/Low Pressure Reverse Osmosis for Water Reuse: Removal of Organic Micropollutants, Fouling and Cleaning

    KAUST Repository

    Linares, Rodrigo

    2011-07-01

    Forward osmosis (FO) is a natural process in which a solution with high concentration of solutes is diluted when being in contact, through a semipermeable membrane, with a low concentration solution. This osmotic process has been demonstrated to be efficient to recover wastewater effluents while diluting a saline draw solution. Nevertheless, the study of the removal of micropollutants by FO is barely described in the literature. This research focuses on the removal of these substances spiked in a secondary wastewater effluent, while diluting water from the Red Sea, generating feed water that can be desalinated with a low pressure reverse osmosis (LPRO) system. Another goal of this work is to characterize the fouling of the FO membrane, and its effect on micropollutants rejection, as well as the membrane cleaning efficiency of different methods. When considering only FO with a clean membrane, the rejection of the hydrophilic neutral compounds was between 48.6% and 84.7%, for the hydrophobic neutrals the rejection ranged from 40.0% to 87.5%, and for the ionic compounds the rejections were between 92.9% and 96.5%. With a fouled membrane, the rejections were between 44.6% to 95.2%, 48.7% to 91.5% and 96.9% to 98.6%, respectively. These results suggest that, except for the hydrophilic neutral compounds, the rejection of the micropollutants is increased by the fouling layer, possibly due to the higher hydrophilicity of the FO fouled membrane compared to the clean one, the increased adsorption capacity and reduced mass transport capacity, membrane swelling, and the higher negative charge of the surface, related to the foulants. However, when coupled with low pressure reverse osmosis, the rejections for both, the clean and fouled membrane, increased above 98%. The fouling layer, after characterizing the wastewater effluent and the concentrated wastewater after the FO process, proved to be composed of biopolymers, which can be removed with air scouring during short periods

  13. An experimental study on the thermal and fouling characteristics in a washable shell and helically coiled heat exchanger by the Wilson plot method

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Kyoung Min; Ahn, Young Chull [Pusan National University, Busan (Korea, Republic of); Hwang, Jun Hyeon; Hur, Hyun; Na, Byung Chul; Hwang, Yoon Jae; Kim, Byung Soon [LG Electronics, Changwon (Korea, Republic of); Lee, Jae Keun [EcoEnergy Research Institute, Busan (Korea, Republic of)

    2016-06-15

    Brazed plate heat exchangers (BPHEX) are broadly used in water source heat pump systems for their large heat transfer capacity. Despite their high heat transfer rate, their high-performance rate tends to decrease sharply, due to fouling and they cannot be cleaned. So the thermal and fouling resistances of washable Shell and helically coiled tube heat exchangers (SCHEX) are designed and experimentally investigated in this study. Heat exchangers with two different tube types are studied and compared with a brazed plate heat exchanger. The overall thermal resistance coefficient of the heat exchangers as determined by using Wilson plots is 38% lower than that of the brazed plate heat exchanger at a Reynolds number of 2460. Fouling test results revealed that regular maintenance and physical cleaning can be used to maintain the thermal resistance of fouling of the washable heat exchanger at a level equal to or less than that of the brazed plate heat exchanger.

  14. Experimental Study of Fouling on Heat Transfer Surface During Forced Convective Heat Transfer%强制对流传热的换热表面结垢特性实验研究

    Institute of Scientific and Technical Information of China (English)

    全贞花; 陈永昌; 马重芳

    2008-01-01

    An experimental study was conducted to investigate the fouling process of calcium carbonate on the heat transfer surface,during forced convective heat transfer.The dynamic monitoring apparatus of fouling resistance was set up for the present experiments.The fouling behaviors were examined under different factors including fluid velocity,hardness,alkalinity,solution temperature,and wall temperature.Asymptotic fouling curves varying with time were obtained.The fouling rate and asymptotic fouling resistance increased and the induction periods were shortened with the fluid velocity decreasing,hardness and alkalinity increasing,and solution temperature and heat transfer surlace temperature lncreasmg.The components of touling that formed on the heat transfer surface included crystallization fouling and particulate fouling.The thermal performance parameter Of fouling,ρfλf,varied from 380 to 2600 kg·W·(m4·K)-1,increasing with growing velocity and decreasing solution ternperature,hardness or alkalinity.Furthermore,the thermal conductivity of fouling,λf,varied from 1.7 to 2.2 W·(m·K)-1.

  15. Costs and benefits to European shipping of ballast-water and hull-fouling treatment: Impacts of native and non-indigenous species

    OpenAIRE

    Fernandes, Jose A.; Santos, Lionel; Vance, Thomas; Fileman, Tim; Smith, David Stanley; Smith, David; Bishop, John D. D.; Viard, Frédérique; Queirós, Ana M.; Merino, Gorka; Buisman, Erik; Austen, Melanie C.

    2016-01-01

    International audience; Maritime transport and shipping are impacted negatively by biofouling, which can result in increased fuel consumption. Thus, costs for fouling reduction can be considered an investment to reduce fuel consumption. Anti-fouling measures also reduce the rate of introduction of non-indigenous species (NIS). Further mitigation measures to reduce the transport of NIS within ballast water and sediments impose additional costs. The estimated operational cost of NIS mitigation ...

  16. Multiple Approaches for Testing Novel Coatings in the Laboratory and in Pearl Harbor, Hawaii with Emphasis on the Global, Problem-Fouling Invertebrates

    Science.gov (United States)

    2015-09-25

    existing protocols for ASTM-based visual inspections, water jet determinations and force gauge measures. (2) We evaluate coatings for removal of...UNIVERSITY OF WASHINGTON JIANG 30 FOUL/RELEASE ANTIFOULING TEXAS A&M UNIVERSITY WOOLEY 16 FOUL/RELEASE ANTIFOULING ZWITTER TECHNOLOGY, LLC LI 9...membrane (Figs. 1A&B), and cell-free filtrates of C. lytica are devoid of bacterial cells yet still induce metamorphosis of H. elegans. OMVs are

  17. Fouling resistance prediction using artificial neural network nonlinear auto-regressive with exogenous input model based on operating conditions and fluid properties correlations

    Science.gov (United States)

    Biyanto, Totok R.

    2016-06-01

    Fouling in a heat exchanger in Crude Preheat Train (CPT) refinery is an unsolved problem that reduces the plant efficiency, increases fuel consumption and CO2 emission. The fouling resistance behavior is very complex. It is difficult to develop a model using first principle equation to predict the fouling resistance due to different operating conditions and different crude blends. In this paper, Artificial Neural Networks (ANN) MultiLayer Perceptron (MLP) with input structure using Nonlinear Auto-Regressive with eXogenous (NARX) is utilized to build the fouling resistance model in shell and tube heat exchanger (STHX). The input data of the model are flow rates and temperatures of the streams of the heat exchanger, physical properties of product and crude blend data. This model serves as a predicting tool to optimize operating conditions and preventive maintenance of STHX. The results show that the model can capture the complexity of fouling characteristics in heat exchanger due to thermodynamic conditions and variations in crude oil properties (blends). It was found that the Root Mean Square Error (RMSE) are suitable to capture the nonlinearity and complexity of the STHX fouling resistance during phases of training and validation.

  18. Biological computation

    CERN Document Server

    Lamm, Ehud

    2011-01-01

    Introduction and Biological BackgroundBiological ComputationThe Influence of Biology on Mathematics-Historical ExamplesBiological IntroductionModels and Simulations Cellular Automata Biological BackgroundThe Game of Life General Definition of Cellular Automata One-Dimensional AutomataExamples of Cellular AutomataComparison with a Continuous Mathematical Model Computational UniversalitySelf-Replication Pseudo Code Evolutionary ComputationEvolutionary Biology and Evolutionary ComputationGenetic AlgorithmsExample ApplicationsAnalysis of the Behavior of Genetic AlgorithmsLamarckian Evolution Genet

  19. Fouling characterization and control for harvesting microalgae Arthrospira (Spirulina) maxima using a submerged, disc-type ultrafiltration membrane.

    Science.gov (United States)

    Kanchanatip, Ekkachai; Su, Bo-Rung; Tulaphol, Sattrawut; Den, Walter; Grisdanurak, Nurak; Kuo, Chi-Chang

    2016-06-01

    This study characterized the fouling of a novel circular-disc ultrafiltration membrane in a submerged bioreactor system to harvest Arthrospira maxima cells. Flux-stepping study showed that the value of critical flux was below the smallest flux tested at 28.8lm(-2)h(-1), and that the membrane was to operate above the critical flux to sustain the necessary rate of cell concentration. The membrane with similar pore size but greater pore density experienced not only lesser degree of total resistance, but also possessed smaller fraction of irreversible resistance. Membrane fouling was mainly attributed to fragmented cells rather than to soluble or extracellular polymeric substances. Furthermore, flux recovery studies demonstrated that membrane relaxation and surface cleaning could partially recover fluxes for both low (6gl(-1)) and high (40gl(-1)) cell densities, whereas backwashing could fully recover fluxes. Calculation of energy consumption and cell harvesting productivity also favoured membrane filtration with backwashing.

  20. Effect of fouling on the capacity and breakthrough characteristics of a packed bed ion exchange chromatography column.

    Science.gov (United States)

    Siu, Sun Chau; Baldascini, Helen; Hearle, David C; Hoare, Mike; Titchener-Hooker, Nigel J

    2006-05-01

    This study examined the impact of fouling with yeast homogenate on capacity and breakthrough performance of an ion exchange packed bed column. Column performance was assessed by analysis of breakthrough curves obtained with BSA as a test protein. The overall impact of fouling on breakthrough performance depended heavily on the level of clarification of the feed stream. Challenging the column with particulate-free homogenate caused no change in column performance. Loading successive small volumes of poorly clarified homogenate, interspersed with frequent column salt washes, did not alter significantly the column capacity. By contrast, when the column was challenged with an equivalent cumulative volume of poorly clarified homogenate, dynamic binding capacity decreased significantly and changes in breakthrough curves suggested increased intraparticle and external mass transfer limitations. These changes were ascribed to deposition of solid particulates in void spaces in the bed and colloidal contaminants in the bead pores.

  1. Investigations into the fouling mechanism of parvovirus filters during filtration of freeze-thawed mAb drug substance solutions.

    Science.gov (United States)

    Barnard, James G; Kahn, David; Cetlin, David; Randolph, Theodore W; Carpenter, John F

    2014-03-01

    Filtration to remove viruses is one of the single most expensive steps in the production of mAb drug products. Therefore, virus filtration steps should be fully optimized, and any decline in flow rates warrants investigation into the causes of such membrane fouling. In the current study, it was found that freezing and thawing of a mAb bulk drug solution caused a substantial decrease in viral filter membrane flow rate. Freezing and thawing also caused formation of aggregates and particles across a broad size range, including particles that could be detected by microflow imaging (≥1 μm in size). However, removal of these particles offered little protection against flow rate decline during viral filtration. Further investigation revealed that trace amounts of aggregates (ca. 10⁻⁶ of the total mass of protein in solution) approximately 20-40 nm in size were primarily responsible for the observed membrane fouling.

  2. Variations in Gas-Turbine Blade Life and Cost due to Compressor Fouling – A Thermoeconomic Approach

    Directory of Open Access Journals (Sweden)

    Magnus Genrup

    2002-03-01

    Full Text Available The connection between gas turbine compressor fouling and expander blade lifetime is studied in a simplified manner for a gas turbine operating in a combined cycle with a constant power output. It is shown how blade materials and compressor fouling rate affect the blade lifetime, and with this background, based on a thermoeconomic approach, the economic aspects of compressor washing intervals and the possibility to find an economic optimum are studied. It is also discussed how it should be possible to employ on-line gas turbine monitoring based on artificial neural networks (ANN in combination with a database containing blade life behavior in order to improve the blade life management strategy for an optimization of power plant life profitability.

  3. Optimization of the Dynamic Behavior of a Heat Exchanger Subject to Fouling Comparison of Three Optimization Models

    Directory of Open Access Journals (Sweden)

    Michel Feidt

    1999-06-01

    Full Text Available

    This paper proposes a dynamic analysis of fouling of a heat exchanger. The used criteria is mean thermal power exchanged over time. The proposed results are relative to cocurrent configuration and tubular geometry of the heat exchanger, but other cases have been explored (countercurrent, plane geometry. An optimum time is determined, sensitivity analysis of the corresponding value to three cases of flow regimes (constant mass flow rate, constant flow velocity and constant pumping power and various kinetics of fouling has been performed. The time of stop of the installation for cleaning is the main parameter. All the results are proposed in nondimensional form.

    •  This paper was presented at the ECOS’98 Conference in Nancy, June 8-10, 1998

  4. Seasonal Patterns of Sporophyte Growth, Fertility, Fouling, and Mortality of Saccharina latissima in Skagerrak, Norway: Implications for Forest Recovery

    Directory of Open Access Journals (Sweden)

    Guri Sogn Andersen

    2011-01-01

    Full Text Available On the Skagerrak coast the kelp Saccharina latissima has suffered severe stand reductions over the last decade, resulting in loss of important habitats. In the present study, healthy kelp plants were transplanted into four deforested areas and their patterns of growth, reproduction, and survival were monitored through subsequent seasons. Our main objective was to establish whether the kelp plants were able to grow and mature in deforested areas. We observed normal patterns of growth and maturation at all study sites. However, heavy fouling by epiphytes occurred each summer, followed by high kelp mortality. The study shows that the seasonal variations and the life stage timing of S. latissima make formation of self-sustainable populations impossible in the present environment. Most noteworthy, we suggest that fouling by epiphytes is involved in the lack of kelp forest recovery in Skagerrak, Norway.

  5. Efficacy and Ecotoxicity of Novel Anti-Fouling Nanomaterials in Target and Non-Target Marine Species.

    Science.gov (United States)

    Avelelas, Francisco; Martins, Roberto; Oliveira, Tânia; Maia, Frederico; Malheiro, Eliana; Soares, Amadeu M V M; Loureiro, Susana; Tedim, João

    2017-03-09

    Biofouling is a global problem that affects virtually all the immersed structures. Currently, several novel environmentally friendly approaches are being tested worldwide to decrease the toxicity of biocides in non-fouling species, such as the encapsulation/immobilization of commercially available biocides, in order to achieve control over the leaching rate. The present study addresses the toxicity of two widely used booster biocides, zinc pyrithione (ZnPT) and copper pyrithione (CuPT), in its free and incorporated forms in order to assess their toxicity and anti-fouling efficacy in target and non-target species. To achieve this goal, the following marine organisms were tested; the green microalgae Tetraselmis chuii (non-target species) and both target species, the diatom Phaeodactylum tricornutum and the mussel Mytilus edulis. Organisms were exposed to both biocides, two unloaded nanostructured materials and nanomaterials loaded with biocides, from 10 μg/L to 100 mg/L total weight, following standard protocols. The most eco-friendly and simultaneously efficient anti-fouling solution against the two photosynthetic species (nanoclays loaded with ZnPT) was then tested on mussels to assess its lethal efficacy (LC50 = 123 μg/L) and compared with free biocide (LC50 = 211 μg/L) and unloaded material (LC50 > 1000 μg/L). A second exposure test with sub-lethal concentrations (lower than 100 μg/L), using mussels, was carried out to assess biochemical changes caused by the tested compounds. Oxidative stress, detoxification and neurotransmission markers were not responsive; however, different antioxidant patterns were found with free ZnPT and loaded nanoclay exposures. Thus, the immobilization of the biocide ZnPT into nanoclays proved to be a promising efficient and eco-friendly anti-fouling strategy.

  6. Remarkable Anti-Fouling Performance of TiO2-Modified TFC Membranes with Mussel-Inspired Polydopamine Binding

    Directory of Open Access Journals (Sweden)

    Rui-Xin Zhang

    2017-01-01

    Full Text Available It has been proven that a versatile bio-glue, polydopamine, can firmly bind TiO2 (titanium dioxide nanoparticles on thin film composite (TFC membranes. In this work, the anti-fouling behaviour of this novel polydopamine-TiO2-modified membrane is evaluated, based on the static bovine serum albumin (BSA surface adhesion of the membranes and the relative flux decline. The results show that the anti-fouling performance of this new membrane is significantly improved in dark conditions when compared with the neat TFC membrane and the membranes only modified by polydopamine or TiO2. When filtrating a 0.5 g·L−1 BSA solution in dark conditions, the flux of the polydopamine-TiO2-modified membrane remains constant, at 95% of its pure water flux after 30 min filtration for 8 h of the experiment. This indicates a significant increase in anti-fouling performance when compared to the 25% flux decline observed for the neat TFC membrane, and to the 15% flux decline of those only modified by polydopamine or TiO2. This remarkable anti-fouling behaviour is attributed to an improved and uniform hydrophilicity, due to the presence of TiO2 and to the regular nanosized papillae structure of the polydopamine-TiO2 coating. Furthermore, since dopamine-modified TiO2 has visible light-induced photocatalytic properties, the membrane’s photocatalytic performance was also tested in light conditions. However an increase of flux and decrease of retention were observed after 24 h of continuous illumination, indicating that light may also affect the top layer of the membrane.

  7. Cleaning results of new and fouled nanofiltration membrane characterized by contact angle, updated DSPM, flux and salts rejection

    Energy Technology Data Exchange (ETDEWEB)

    Al-Amoudi, Ahmed [Centre for complex fluids processing, Multidisciplinary Nanotechnology Centre, School of Engineering, University of Wales, Swansea SA2 8PP (United Kingdom) and Saline Water Conversion Corporation (SWCC), Saline Water Desalination Research Institute Staff (Saudi Arabia)], E-mail: 310981@swan.ac.uk; Williams, Paul [Centre for complex fluids processing, Multidisciplinary Nanotechnology Centre, School of Engineering, University of Wales, Swansea SA2 8PP (United Kingdom); Al-Hobaib, A.S. [Institute of Atomic Energy Research, King Abdulaziz City for Science And Technology, P.O. Box 6086, Riyadh 11442 (Saudi Arabia); Lovitt, Robert W. [Centre for complex fluids processing, Multidisciplinary Nanotechnology Centre, School of Engineering, University of Wales, Swansea SA2 8PP (United Kingdom)

    2008-04-30

    In membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. Though cleaning is important to recover membrane performance, an inappropriate selection of cleaning agents may result into unsatisfactory cleaning or irreparable membrane. In this study the cleaning performance has been studied with measurements of membrane contact angle, Updated Donnan steric partitioning pore model (UDSPM) and salt rejection as well as flux measurement. Thin film nanofiltration (NF) membranes such as DK, HL and DL provided by GE Osmonics are used in this study. Tests were carried out with virgin DK, HL and DL as well as fouled DK membranes. Several cleaning agents were investigated; some of them were analytical grade such as HCl, NaOH and others such as SDS, mix agents were commercial grade agents that are already in use in commercial plants. Contact angle, DSPM and salt rejection as well as flux of virgin and fouled membranes before and after chemical cleaning were measured and compared. The contact angle measurements with and without chemical cleaning of different virgin and fouled membranes revealed very interesting results which may be used to characterise the membrane surface cleanliness. The contact angle results revealed that the cleaning agents are found to modify membrane surface properties (hydrophobicity/hydrophilicity) of the treated and untreated virgin and fouled membranes. The details of these results were also investigated and are reported in the paper. However, UDSPM method did not give any valuable information about pore size of the untreated and treated NF membranes. The salt rejection level of monovalent and divalent ions before and after cleaning by high and low pH cleaning agents is also investigated and is reported in the paper.

  8. Addressing reverse osmosis fouling within water reclamation--a side-by-side comparison of low-pressure membrane pretreatments.

    Science.gov (United States)

    Kent, Fraser C; Farahbakhsh, Khosrow

    2011-06-01

    A tertiary membrane filtration (TMF) pilot operating on secondary effluent and a membrane bioreactor (MBR) were setup in a side-by-side study as pretreatments for two identical reverse osmosis pilot systems. The water quality of the permeate from both low-pressure membrane pretreatment systems and the fouling rate of the reverse osmosis systems were compared to assess the capabilities of the two low-pressure membrane pretreatments to prevent organic fouling of the reverse osmosis systems. Both pretreatment pilots were setup using typical operating conditions (i.e., solids retention time and mixed-liquor suspended solids). A consistent difference in water quality and reverse osmosis performance was demonstrated during the 12-month study. The MBR permeate consistently had significantly lower total organic carbon (TOC) and chemical oxygen demand concentrations, but higher color and specific UV absorbance compared with the permeate from the TMF pretreatment. The pretreatment with the MBR gave an average reverse osmosis fouling rate over the entire study (0.27 Lmh/bar.month) that was less than half of the value found for the reverse osmosis with TMF pretreatment (0.60 Lmh/bar.month). A correlation of reverse osmosis feed TOC concentration with average reverse osmosis fouling rate also was established, independent of the pretreatment method used. Results from a cleaning analysis, energy dispersive spectroscopy, and fourier transformed infrared reflectometry confirmed that the foulants were primarily organic in nature. It is concluded that, for this type of application and setup, MBR systems present an advantage over tertiary membrane polishing of secondary effluent for reverse osmosis pretreatment.

  9. In-line coagulation prior to UF of treated domestic wastewater - foulants removal, fouling control and phosphorus removal

    KAUST Repository

    Zheng, Xing

    2012-06-01

    The present work investigated fouling control and phosphorus removal by applying in-line coagulation prior to ultrafiltration (UF) of treated domestic wastewater. Experiments were conducted in both lab- and pilot-scale under close to neutral pH condition. Lab-scale foulant removal tests showed that increasing the dosage of FeCl3, AlCl3 and polymeric aluminum chloride (PACl) can improve biopolymer removal. Specifically, PACl reduced preferentially the proteinaceous fraction of biopolymer while the other two coagulants showed no significant preference. The filterability of water samples was improved after coagulation, which is contributed to biopolymer removal and the formation of larger particles. Pilot UF experiments demonstrated that in-line coagulation improved the performance of UF to a large extent. Within 0.037-0.148mmol Me3+/L dosage range, adding more FeCl3 and AlCl3 slowed down the development of trans-membrane pressure (TMP) correspondingly, while changing PACl dosage showed little effect on the variation of TMP increase rate. Further investigations indicated that PACl related precipitates contributed to more irreversible fouling than that which the monomeric coagulants made. Fouling control is thus considered as a co-effect determined by foulant removal efficiency, fouling layer structure and the adherence of hydrolysis products/precipitates onto the membrane. With respect to phosphorus removal, dosing FeCl3 and AlCl3 achieved higher removal efficiency than using PACl. Based on lab- and pilot-scale results, dosing FeCl3 and AlCl3 at a relative dosage of over 2.5mol Me3+ per mol total phosphorus (TP) in feedwater is necessarily required to keep the TP concentration under 50μg/L in UF permeate. © 2012 Elsevier B.V.

  10. Irreversible fouling of membrane bioreactors due to formation of a non-biofilm gel-like layer

    DEFF Research Database (Denmark)

    Poorasgari, Eskandar; Larsen, Poul; Zheng, Xing

    2013-01-01

    adsorption kinetics. Due to static adsorption, surface roughness of the membrane declined significantly indicating that adsorbed matters to the membrane filled the cavities of the membrane surface. Filtration of the free EPS caused 50% water flux decline. The fouling resistance linearly increased...... with the amount of the humic-like substances retained during filtration as predicted by gel growth theory. A low pressure backwash could re-establish the water flux only up to 70%....

  11. Sunlight-Sensitive Anti-Fouling Nanostructured TiO2 coated Cu Meshes for Ultrafast Oily Water Treatment

    Science.gov (United States)

    Liu, Haoran; Raza, Aikifa; Aili, Abulimiti; Lu, Jinyou; Alghaferi, Amal; Zhang, Tiejun

    2016-05-01

    Nanostructured materials with desired wettability and optical property can play an important role in reducing the energy consumption of oily water treatment technologies. For effective oily water treatment, membrane materials with high strength, sunlight-sensitive anti-fouling, relative low fabrication cost, and controllable wettability are being explored. In the proposed oily water treatment approach, nanostructured TiO2-coated copper (TNS-Cu) meshes are used. These TNS-Cu meshes exhibit robust superhydrophilicity and underwater oleophobicity (high oil intrusion pressure) as well as excellent chemical and thermal stability (≈250 °C). They have demonstrated high separation efficiency (oil residue in the filtrate ≤21.3 ppm), remarkable filtration flux (≥400 kL h‑1 m‑2), and sunlight-sensitive anti-fouling properties. Both our theoretical analysis and experimental characterization have confirmed the enhanced light absorption property of TNS-Cu meshes in the visible region (40% of the solar spectrum) and consequently strong anti-fouling capability upon direct solar light illumination. With these features, the proposed approach promises great potential in treating produced oily wastewater from industry and daily life.

  12. Fluorescence analysis of NOM degradation by photocatalytic oxidation and its potential to mitigate membrane fouling in drinking water treatment.

    Science.gov (United States)

    Nerger, Bryan A; Peiris, Ramila H; Moresoli, Christine

    2015-10-01

    This study examined the photocatalytic oxidation of natural organic matter (NOM) as a method to mitigate membrane fouling in drinking water treatment. ZnO and TiO2 photocatalysts were tested in concentrations ranging from 0.05 g L(-1) to 0.5 g L(-1). Fluorescence peaks were used as the primary method to characterize the degradation of three specific NOM components - fulvic acid-like humic substances, humic acid-like humic substances, and protein-like substances during photocatalytic oxidation. Fluorescence peaks and Liquid Chromatography-Organic Carbon Detection (LC-OCD) analysis indicated that higher NOM degradation was obtained by photocatalytic oxidation with ZnO than with TiO2. Treatment of the feed water by ZnO photocatalytic oxidation was successful in reducing considerably the extent of hydraulically reversible and irreversible membrane fouling during ultrafiltration (UF) compared to feed water treatment with TiO2. Fouling during UF of water subjected to photocatalytic oxidation appeared to be caused by low molecular weight constituents of NOM generated during photocatalytic oxidation.

  13. Research and development to overcome fouling of membranes. First annual report, October 1, 1989--October 31, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Narang, S.C.; Sharma, S.K.; Ventura, S.C.; Roberts, D.L.; Ahner, N.

    1992-06-01

    During this first year of the program, we have successfully accomplished the main objective of demonstrating the feasibility of using piezoelectrically assisted ultrafiltration to reduce membrane fouling and enhance the flux through ultrafiltration membranes. A preliminary economic evaluation, accounting for the power consumption of the piezoelectric driver and the extent of permeate flow rate enhancement, has also shown that piezoelectrically assisted ultrafiltration is cost effective and economically competitive with traditional separation processes. Piezoelectric transducers, such as a piezoelectric lead zirconate titanate (PZT) disc or a piezoelectric horn, driven by moderate power, significantly enhance the permeate flux on fouled membranes, presumably because they promote local turbulence. Several experiments were conducted on polysulfone and regenerated cellulose UF membranes fouled during filtration of model feed solutions. Solutions of poly(ethylene glycol) and of high-molecular weight dextran were used as models. We found that we could significantly increase the permeate flux by periodically driving the piezoelectric transducer, horn, or PZT disc, by application of moderate power over short periods of time, from 20 to 90 seconds. Enhancements as high as a factor of 8 were recorded with a few seconds, and enhanced permeate fluxes were maintained over a prolonged period (up to 3 hours). The prolonged flux enhancement makes it feasible to drive the piezoelectric transducer intermittently, thereby reducing the power consumption of the piezoelectric driver.

  14. Fouling characteristics of reverse osmosis membranes at different positions of a full-scale plant for municipal wastewater reclamation.

    Science.gov (United States)

    Tang, Fang; Hu, Hong-Ying; Sun, Li-Juan; Sun, Ying-Xue; Shi, Na; Crittenden, John C

    2016-03-01

    Membrane fouling is an important shortcoming limiting the efficiency and wide application of reverse osmosis (RO) technology. In this paper, RO membranes in a full-scale municipal wastewater reclamation plant were autopsied. From the lead to tail position RO membranes in RO system, both of organic and inorganic matters on membranes reduced gradually. The higher ion products in RO concentrate didn't result in more serious inorganic scaling on the last position RO membranes, which was contrast with some other researches. Fe, Ca and Mg were major inorganic elements. Fe had a relatively low concentration in RO influent but the highest content on membranes. However, there was no specific pretreatment in terms of Fe removal. Ca and Mg scaling was controlled by the antiscalants injected. Organic fouling (75.0-84.5% of dry weights) was major problem on RO membranes due to the large amount of dissolved organic matters in secondary effluent as raw water. Hydrophilic acid (HIA, 48.0% of total DOC), hydrophobic acid (HOA, 23.6%) and hydrophobic neutral (HON, 19.0%) fraction was largest among the six fractions in RO influent, while HON (38.2-51.1%) and HOA (22.1-26.1%) tended to accumulate on membranes in higher quantities. Monitoring HON and HOA might help to forecast organic fouling.

  15. Advanced Wastewater Treatment Engineering-Investigating Membrane Fouling in both Rotational and Static Membrane Bioreactor Systems Using Empirical Modelling.

    Science.gov (United States)

    Paul, Parneet; Jones, Franck Anderson

    2016-01-05

    Advanced wastewater treatment using membranes are popular environmental system processes since they allow reuse and recycling. However, fouling is a key limiting factor and so proprietary systems such as Avanti's RPU-185 Flexidisks membrane bioreactor (MBR) use novel rotating membranes to assist in ameliorating it. In earlier research, this rotating process was studied by creating a simulation model based on first principles and traditional fouling mechanisms. In order to directly compare the potential benefits of this rotational system, this follow-up study was carried out using Avanti's newly developed static (non-rotating) Flexidisks MBR system. The results from operating the static pilot unit were simulated and modelled using the rotational fouling model developed earlier however with rotational switching functions turned off and rotational parameters set to a static mode. The study concluded that a rotating MBR system could increase flux throughput when compared against a similar static system. It is thought that although the slowly rotating spindle induces a weak crossflow shear, it is still able to even out cake build up across the membrane surface, thus reducing the likelihood of localised critical flux being exceeded at the micro level and lessening the potential of rapid trans-membrane pressure increases at the macro level.

  16. Molecular fouling resistance of zwitterionic and amphiphilic initiated chemically vapor-deposited (iCVD) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R; Goktekin, E; Wang, MH; Gleason, KK

    2014-08-08

    Biofouling is a universal problem in various applications ranging from water purification to implantable biomedical devices. Recent advances in surface modification have created a rich library of antifouling surface chemistries, many of which can be categorized into one of the two groups: hydrophilic surfaces or amphiphilic surfaces. We report the straightforward preparation of antifouling thin film coatings in both categories via initiated chemical vapor deposition. A molecular force spectroscopy-based method is demonstrated as a rapid and quantitative assessment tool for comparing the differences in antifouling characteristics. The fouling propensity of single molecules, as opposed to bulk protein solution or bacterial culture, is assessed. This method allows for the interrogation of molecular interaction without the complication resulted from protein conformational change or micro-organism group interactions. The molecular interaction follows the same trend as bacterial adhesion results obtained previously, demonstrating that molecular force probe is a valid method for the quantification and mechanistic examination of fouling. In addition, the molecular force spectroscopy-based method is able to distinguish differences in antifouling capability that is not resolvable by traditional static protein adsorption tests. To lend further insight into the intrinsic fouling resistance of zwitterionic and amphiphilic surface chemistries, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, advancing and receding water contact angles, and atomic force microscopy are used to elucidate the film properties that are relevant to their antifouling capabilities.

  17. Comparative experimental study on fouling mechanisms in nano-porous membrane: cheese whey ultrafiltration as a case study.

    Science.gov (United States)

    Torkamanzadeh, Mohammad; Jahanshahi, Mohsen; Peyravi, Majid; Shokuhi Rad, Ali

    2016-12-01

    Determination of fouling mechanisms and accurate quantitative prediction of nano-porous membrane behavior are of great interest in membrane processes. This work has focused on a comprehensive comparison of two classical and new fouling models. Different operational conditions were tested to analyze the level of agreement of these models with experimental observation. Whey solutions of 8, 0.8 and 0.5 g/L were ultrafiltered in transmembrane pressures (TMPs) of 300 and 500 KPa through a synthesized polyethersulfone/copolymer blend membrane. Fouling mechanisms and the effect of different combinations of TMPs and protein concentrations were determined and analyzed by fitting the experimental data to different models. Based on the results obtained from classical models, it was found that the predictions of the cake layer formation model were quite acceptable, followed by the intermediate blocking model. The new combined pore blockage-cake filtration model, however, was found to be very successful in predicting the flux decline over time for every operational condition tested, with all relative errors of prediction less than 5%. The latter also showed a good performance in the transition from the pore blockage mechanism to cake layer formation.

  18. Synthesis and characterization of polyester thin film composite membrane via interfacial polymerization: Fouling behaviour of uncharged solute

    Science.gov (United States)

    Mah, K. H.; Yussof, H. W.; Seman, M. N. A.; Mohammad, A. W.

    2016-11-01

    Most hydrolysis studies on biomass in Malaysia produce high amount of xylose and glucose compared to other monosaccharides and most of them are acidic. Thin film composite (TFC) membrane developed via interfacial polymerization using triethanolamine (TEOA) and trimesoyl chloride (TMC) as monomers allows separation at low pH to occur without damaging its performance. Comparative studies were carried out on membranes with and without the thin film layer formed via interfacial polymerization on the polyethersulfone (PES) support. The surfaces of the membranes were characterized by field emission scanning electronic microscopy (FESEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and hydrophilicity via contact angle measurement. In addition, the performance and uncharged solute fouling behaviour of TFC membrane were also investigated. The TFC membrane used for characterization purposes was prepared at TEOA concentration of 4 % w/v in 1 × 10-6 M sodium hydroxide solution, TMC concentration of 0.25 % w/v in pure hexane, reaction time of 45 minutes, and cured at temperature of 60 °C. Characterization results showed a huge different between the synthesized TFC membrane and the un-synthesized PES membrane in term of surface properties and morphology. Nanofiltration results indicate that the formation of thin layer on top of PES support membrane improved the separation performance compared to PES support membrane. The synthesised polyester TFC membrane have irreversible fouling of 11.02 (±5.60) % and reversible fouling of 5.59 % using water as cleaning agent.

  19. Ultrafiltration with in-line coagulation for the removal of natural humic acid and membrane fouling mechanism

    Institute of Scientific and Technical Information of China (English)

    WANG Jin; WANG Xiao-chang

    2006-01-01

    Experimental and theoretical analysis were made on the natural humic acid removal and the membrane fouling of ultrafiltration (UF) with in-line coagulation. The results showed dissolved organic carbon (DOC) and UV254 removals by the UF with in-line coagulation at pH 7 were increased from 28% to 53% and 40% to 78% in comparison with direct UF treatment respectively. At the same time, the analysis of high performance liquid chromatography showed that UF with coagulation had significant improvement of removal of humic acid with molecular weights less than 6000 Da in particular. Compared to direct UF, the in-line coagulation UF also kept more constant permeate flux and very slight increase of transmembrane pressure during a filtration circle.Two typical membrane fouling models were used by inducing two coefficients Kc and Kp corresponding to cake filtration model and pore narrowing model respectively. It was found that membrane fouling by pore-narrowing effect was effectively alleviated and that by cake-filtration was much decreased by in-line coagulation. Under the condition of coagulation prior to ultrafiltration at pH 7,the cake layer formed on the membrane surface became thicker, but the membrane filtration resistance was lower than that at pH 5 with the extension of operation time.

  20. The use of microbial and chemical analyses to characterize the variations in fouling profile of seawater reverse osmosis (SWRO) membrane

    KAUST Repository

    Manes, Carmem Lara De O

    2013-01-01

    Biofouling of reverse osmosis (RO) membranes is one of the most common problems in desalinations plants reducing the efficiency of the water production process. The characterization of bacterial community composition from fouling layers as well as detailed analysis of surrounding chemical environment might reveal process specific bacterial groups/species that are involved in RO biofouling. In this study, advanced organics analytic methods (elemental analysis, FTIR, and ICP-OES) were combined with high-throughput 16S rRNA (pyro) sequencing to assess in parallel, the chemical properties and the active microbial community composition of SWRO membranes from a pilot desalination plant (MFT, Tarragona) in February 2011 and July 2011. Prefiltered ultrafiltration. waters fed SWRO membranes during third and fifth month of operation, respectively. SWRO samples were taken from three modules at different positions (first, fourth, and sixth) in order to investigate the spatial changes in fouling layers\\' chemical and microbiological composition. The overall assessment of chemical parameters revealed that fouling layers were mainly composed by bio and organic material (proteins and lipids). Ca and Fe were found to be the most abundant elements having an increasing concentration gradient according to the module position. Bacterial community composition of SWRO membranes is mostly represented by the Gammaproteobacteria class with interesting differences in genera/species spatial and temporal distribution. This preliminary result suggests that pretreatments and/or operational conditions might have selected different bacterial groups more adapted to colonize SWRO membranes. © 2013 Desalination Publications.